"I shall crush you like an insect!! For I am Fin Fang Foom!"
A comic book character, owned by Marvel Comics. He made his debut in 1961's "Strange Tales #89", one of Marvel's many "giant monster" comics of the 1950s and '60s. The story is credited to Stan Lee, though Larry Leiber may have been the author. Jack Kirby did the art, and there ain't nobody who disputes that.
Fin Fang Foom is a gigantic Chinese dragon who, for some unknown reason, wears purple underpants. Maybe he's shy. No, wait, he's not shy -- he's a fearsome butt-whuppin' monstrosity! All must flee before the awesome power of Fin Fang Foom! In a desperate ploy to stop a planned Chinese invasion of Formosa, a history student awakens the monster from his centuries-long slumber with a magical herb, then taunts the dragon until he goes on a rampage, wrecking part of the Great Wall of China and stomping all over the Red Army. At last, with the invasion foiled before it even began, the student tricks Fin Fang Foom back into his cave and puts him back to sleep with another magical herb. Huzzah!
Of course, you can't put Fin Fang Foom down for the count with measly herbs! The arrogant and loud-mouthed dragon was a fan favorite and returned multiple times, both in regular monster stories and in conflict with Marvel's superheroes, including Thor and Iron Man. He was supposedly killed in an issue of "Iron Man", but think you to permanently bar the beast from comics? FOOLS! Dare you mock his giant purple underoos?! Fin Fang Foom will destroy you ALL!
Addendum: Transitional Man notes that Fin Fang Foom was revealed to be Jormungand during Walt Simonson's run on "Thor".
Addendum Addendum: Habakkuk adds, "Actually, Jormungand disguised himself as Fin Fang Foom for a time. In the Marvel timeline, Jormungand has been killed, but Fin Fang Foom has since been used in an Iron Man comic as a tie-in to the dragon people that crashlanded and from their ship the Mandarin got his funky rings. It is all quite confusing, but it is Marvel then." Ahem. What he said.
Addendum Addendum Addendum: Gamaliel says, "I think the Comics Code made Kirby put pants on him..." Well, yeah, but the stuff about Foom wearing 'em 'cause he's shy is Comedy Gold! ;)
Research from http://members.aol.com/ojerasmus/finff.html