David choosing "Grate Aural Sects" as an example to illustrate the idea of saying the same thing but writing it differently.
The scene with David and Jill on the balcony when her research has been challenged.
Any time David interacts with Titus Muyrbridge. I confess to doing a ginger ale spit-take (hard enough that some found its way into my nose - IT BURNS) the first time I heard "Auflander Duckfucker." Crass and juvenile, but then you realize who's saying it and it fits oh-so-well.
Subtle but highly entertaining example when one of the symptoms of some latter-day Gulf War Syndrome are said to include "serious hair loss", prompting an utterly deadpan remark that, "All hair-loss is serious," from Carlos.
David's 'Havid and Dung' explanation of horizontal transfer to General Hung.
Carlos is advising Joanna not to sleep with David (after the two of them have been making eyes at each other all episode), arguing that "sometimes David uses women". Her retort is that "sometimes I can use men". After David has walked in and Carlos has explained that he and Joanna used to be married, Joanna tells David, "He seems to think that you and I have a lot in common." David's response is a most hilariously intrigued "Really?"
Just after Jill leaves David in his hotel room in New York, there is a knock on the door. David, being the genius he is, walks naked to the door and opens it, expecting it to be Jill. Instead, it's a couple of authorities of some sort. After a moment he has the presence of mind to cover his privates, but then promptly forgets it when he offers one of the men his hand. Their expressions really make this one.