Dave Letterman drops the F-bomb on giggling guest Tom Cruise

Bad words can be pretty funny ... especially when they're said on the kind of television that's not, you know, HBO.

Guest star Tom Cruise broke into a giggling fit on "Late Night with David Letterman" after his host purposefully dropped what was previously teased as "the F-word" while describing a recent conversation with his son.

"Good night, everyone!" Letterman joked as Cruise and the audience broke into laughter, with the cameraman joining in on the joke for a moment by pulling out to a wider shot as if the show were ending. Check out the clip below:

Letterman and Cruise were discussing having the dreaded "sex ed" talk, with Dave admitting he might be behind the curve on that when it comes to his nine-year-old son, Harry. However, father and son have had a conversation about "dirty words," specifically "the S-word," "the B-word" and, of course, "the F-word."

"So you hang on, and you ask, 'Okay, what is the S-word?' and he says 'Stupid,'" said Letterman, to the delight of Cruise and the audience. "And I said, 'And what about the B-word?' and he said 'Bad.'"

"And I said, 'And the F-word?' and he said 'F**k.'"

The censors caught it, putting in a goofy Warner Bros. cartoon-esque sound in its place, though a laughing Cruise didn't think that was going to be enough. "Someone's got the plug and they're pulling it!" he said after Letterman mockingly said farewell to the audience.

This latest F-bomb incident went over a lot better than Tom Hanks' recent slip-up, who accidentally dropped the word when imitating one of his more profane characters in "Cloud Atlas" while on "Good Morning America" this past October. Both Hanks and interviewer Elizabeth Vargas seemed genuinely embarrassed, with Vargas even quickly apologizing to the audience and staff.

Cruise was on "Late Night with David Letterman" to promote his new action thriller, "Jack Reacher," which recently cancelled its Pittsburgh premiere and special NYC screening upon the aftermath of the Connecticut shootings. The film opens December 21.