Appellant Reyes-Vasquez (“Reyes”), convicted of possessing cocaine with intent to distribute it, challenges his conviction in four ways, only one of which has sufficient merit to discuss in detail.1
Reyes was arrested after trying to sell seven kilograms of cocaine to Amato2, an undercover Drug Enforcement Administration (DEA) agent. Reyes denies neither that he was in possession of the cocaine nor that he intended to give it to Amato. Instead, Reyes claims that he set up the *1499cocaine transaction pursuant to his work in a CIA-run intelligence operation designed to infiltrate a leftist Colombian terrorist organization, M-19.
After bringing Reyes into the United States, giving him cash and papers, and moving him to Miami, the CIA — Reyes says — instructed him to arrange a drug deal with Correa and Portell, two suspected M-19 members. After Reyes negotiated the terms of a cocaine deal with Correa and Ported, these two brought a large quantity of cocaine to Reyes’ home. According to Reyes, while the CIA was staking out his house, Reyes negotiated a selling price with Amato, who was to buy the cocaine supplied by Correa and Ported. After Am-ato left the house pretending to get the purchase money from his car, DEA agents, including Amato, rushed in and arrested Correa and Reyes.3
Reyes claims the CIA intended to “arrest” Correa and Ported and to use the threat of criminal prosecution to persuade them to act as informants for the CIA. Neither the CIA nor Reyes knew, however, that Ported was a confidential informant for the DEA; after Ported gave the DEA advance notice of the drug transaction, the DEA — apparently unaware of the CIA agents who were allegedly staking out the house at precisely the same time — made the raid. Under Reyes’ version of the facts, when the CIA agents staking out the house saw the DEA arrive, the CIA melted away and left him to be arrested.
In United States v. Rosenthal, 793 F.2d 1214, 1235-37 (11th Cir.1986), modified on other grounds, 801 F.2d 378 (11th Cir.1986), we rejected a similar “CIA intelligence gathering” defense. Relying on Rosenthal, the trial court granted the government’s pretrial motion to prohibit testimony about Reyes’ CIA authority.4 After this grant, Reyes’ counsel refused to take part in the trial, at the conclusion of which the jury returned a guilty verdict. Reyes appeals the grant of the government’s motion to exclude evidence, which we review for abuse of discretion. See United States v. Russell, 703 F.2d 1243, 1249 (11th Cir.1983).
Reyes argues that the trial court should have allowed testimony about his CIA involvement; he claims his belief that the CIA had the authority to conduct drug “sting” operations should exonerate him. The CIA, however, possesses no authority to violate federal narcotics laws, see Executive Order No. 12333, 3 C.F.R. 200 (1982); and Reyes’ proffered defense fails as a matter of law, Rosenthal, 793 F.2d at 1236.
At oral argument on this appeal, Reyes tried to cast this contention in a different light, arguing that testimony about the CIA is relevant to determine whether he had the specific intent to distribute cocaine, an essential element of his crime. But because Reyes failed to argue in the district court that he never intended to deliver cocaine to another person, we decline to address the argument here. See Wu v. Thomas, 847 F.2d 1480, 1484-85 (11th Cir.1988); Lim v. Central DuPage Hosp., 871 F.2d 644, 647-48 (7th Cir.1989).
In presenting arguments to busy trial courts, subtlety is no virtue. As we read the record, Reyes failed to raise, and the trial court did not bar, the “no-intent-to-distribute” defense. In Reyes’ appellate reply brief, he states that “[t]he complete *1500exposition of the defense theory, and argument on all defense motions, can be properly found at T. Vol. I, p. 3, line 8 through page 21, line 14; pp. 34, line 17 through page 50, line 23. Also T. Yol. II, January 17, 1989, pp. 2 through 9, line 16; p. 73, lines 8-14; p. 74, lines 7-11; p. 75, line 23 through page 76, line 8.” In this “complete exposition,” Reyes fails to raise the no-intent-to-distribute issue; he relies exclusively on his “public authority” and “entrapment by estoppel” defenses foreclosed by Rosenthal.5
In addition, the context of the passage from Reyes’ trial brief quoted by the dissent shows that Reyes failed to raise the intent-to-distribute issue directly. The language, quoted here in full, reads: “Contrary to page 3 of the Government’s motion, the issue of the accused’s lack of criminal intent to distribute the controlled substance is the sole issue of the accused’s trial defense: good faith reliance/entrapment by estoppel.” T.R. Tab 51. The use of the colon before “good faith reliance/entrapment by estoppel” clarifies the argument. See M. Shertzer, The Elements of Grammar 93 (1986) (colon precedes restatement or explanation of idea); K. Gordon, The Well-Tempered Sentence 61 (1983) (colon used to introduce part of sentence that explains, restates, or explains preceding part). Thus, Reyes’ “lack of criminal intent” defense was based on the idea that a good-faith belief that he was acting under the authority of the CIA should exonerate him even if his conduct was otherwise unlawful. As we note above, Rosenthal forecloses Reyes’ “CIA-authority” defense; and we do not believe the trial brief asserts the separate defense of Reyes’ lack of intent to pass cocaine to others, even to CIA agents. Considering the broad statutory definitions of “deliver,” “delivery,” “distribute,” and “distributor,” we doubt that Reyes’ no-intent-to-distribute defense, even if asserted, would have been persuasive.6 This may explain why Reyes’ trial counsel failed to assert it.
Plain talk by lawyers is necessary for clear understanding by judges. “Whenever a litigant has a meritorious proposition of law which he is seriously pressing upon the attention of the trial court, he should raise that point in such clear and simple language that the trial court may not misunderstand it, and if his point is so obscurely hinted at that the trial court quite excusably may fail to grasp it, it will avail naught to disturb the judgment on appeal.” Clark v. Lindley Motor Co., 126 Kan. 419, 268 P. 860, 861 (1928) (quoted in United States v. Madruga, 810 F.2d 1010, 1014 n. 7 (11th Cir.1987)). In arguing against the government’s motion to exclude evidence, Reyes’ trial counsel made a lengthy, fact-oriented argument to the effect that Reyes believed that CIA involvement precluded his conduct from being criminal. It requires imagination to find here — based on a single line in a pretrial motion, unsupported by any part of a lengthy oral argument on that motion in district court — an entirely different defense: that is, that Reyes had no intent to pass cocaine to others. As Reyes’ presented his defense to the district court, he — at most — hinted at a no-intent-to-pass-the-cocaine-on argument. As we have stated, “[w]e decline to add the duty to interpret imaginatively what lawyers say to the long list of responsibilities of magistrates and other trial judges.” Madruga, 810 F.2d at 1014.
We reject the use of plain error in this case to reverse the trial court’s judg*1501ment. First, we stress that the doctrine is to be applied sparingly, or the rule about the need to preserve errors for appeal by timely objection in the trial court will be swallowed by the plain error exception. Second, by its terms, recourse may be had to the doctrine “only on appeal from a trial infected with error so ‘plain’ that the trial judge and prosecutor were derelict in countenancing it, even absent the defendant’s timely assistance in detecting it.” United States v. Frady, 456 U.S. 152, 163, 102 S.Ct. 1584, 1592, 71 L.Ed.2d 816 (1982); see also United States v. Gerald, 624 F.2d 1291, 1299 (5th Cir.1980) (“plain error is error which is both ‘obvious and substantial’ _ The plain error rule is not a run-of-the-mill remedy. The intention of the rule is to serve the ends of justice; therefore, it is invoked ‘only in exceptional circumstances [where necessary] to avoid a miscarriage of justice.’”) (quoting Eaton v. United States, 398 F.2d 485, 486 (5th Cir.1968)).
We see no plain and obvious error. Here, the government motion to exclude evidence sought to bar the public authority defense: that if Reyes thought he was acting pursuant to CIA authority, his conduct was not intended to be criminal and could not violate the law. The government filed no motion asking the court to bar Reyes from presenting evidence that he never intended to distribute — that is, to pass to others as opposed to hold or to use himself — cocaine. In a similar manner, the district court’s order in this case did not bar Reyes from arguing or from presenting evidence that he had no intent to distribute cocaine. Instead, the order was limited to the defense of public authority and the related estoppel defense. Because the district court did not exclude evidence of Reyes’ lack of intent to distribute, we cannot say that the court plainly erred by excluding such evidence.
The district judge stressed that he wanted Reyes to preserve an appeal on all the issues that Reyes wished to preserve. The judge also told Reyes that he would allow proffers during the trial to ensure that Reyes could perfect his record for appeal and sharpen the issues as Reyes saw fit. Reyes’ counsel made no proffers before or during trial about Reyes’ lack of intent to distribute.
AFFIRMED.
. Reyes claims the trial court improperly prevented him from obtaining various CIA files and the addresses of Portell, the confidential informant, and Mendez, who was allegedly Reyes’ CIA case officer. But because Reyes requested these files and these locations to prove a defense that is invalid in any event, the trial court was within its discretion in denying access.
Reyes also mounts a fifth amendment challenge to the sentencing guidelines, a claim which is foreclosed by our recent holding in United States v. Erves, 880 F.2d 376, 379 (11th Cir.1989).
. Although the record and the appellant's brief refer to this individual as “Amaro," the government's brief refers to him as "Amato.” Both of these references are to the same person.
. Criminal charges against Correa were dropped for unrelated reasons.
. The trial court granted the government’s motion as follows:
Concerning the Government's motion in li-mine to preclude the defendant’s reliance on the public authority defense, that motion is granted based upon [Rosenthal].
I find that case and the facts in this case to be on all fours. I also reject the concept of the estoppel defense raised in this case for two reasons.
Number one, because I think it is basically just a back way of arguing the public authority defense in the Talmadge [sic] case [United States v. Tallmadge, 829 F.2d 767 (9th Cir.1987) ], and I don’t think that is a legally cognizable defense under the facts presented.
So I am striking those defenses and instructing defense counsel there will be no elicitation of those defenses during the trial of this case starting Tuesday morning.
T.R. 1-44-45.
. Briefly stated, entrapment by estoppel may apply when a government official incorrectly tells a defendant that certain conduct is legal and the defendant reasonably believes the official. In such a case, the government's and the defendant's reliance on that statement may operate to estop the government from convicting the defendant. See United States v. Tallmadge, 829 F.2d 767 (9th Cir.1987). Under the public authority defense, the defendant says that his actions were taken under color of public authority. See United States v. Rosenthal, 793 F.2d 1214, 1236-37 (11th Cir.1986).
. See 21 U.S.C.A. § 802(8) (West Supp.1990) (“The terms 'deliver' or ‘delivery’ mean the actual, constructive, or attempted transfer of a controlled substance or a listed chemical, whether or not there exists an agency relationship."); id. at § 802(11) (“The term ‘distribute’ means to deliver (other than by administering or dispensing) a controlled substance or listed chemical. The term ‘distributor’ means a person who so delivers a controlled substance or a listed chemical.").