THere are alot of funny episodes, here's a rundown of the few that I think are overly hilarious.
1) Storyteller-In my opinion THE funniest ever. Tom Lenk did a really good job coming off not only funny, but you got a feel for Andrew. So many funny moents in this episode, "We Are As Gods" being my favorite, The Romance Novel sequence, Andrew riping on Buffy's speeches, special appearance by The Cheeseman made this the all time funniest in a pretty serious season.
2)Restless- Not only was this a genius concept, but it also gave us one fo the funniest monets on Buffy, I'm talking about the weird version of "Death Of A Salesman". Even people who absolutely hate Riley, should atleast appreciate the good job he did as "Cowboy guy". Not to mention Anya learing how to drive by just gesturing rapidly, Giles song, Spike posing, Riley becoming the surgeon general and defending The Intiative by building a fort made out of cshions and sheets, and The CheeseMan.
3) SuperStar- I'm going to say this just once, Jonothan should've became a Scoob, he was funny yet serious all in one. And you have got to love the the opening credits for that episode.
4) Doomed- Mainly in part to Spike fighting demons in a pair of khaki shorts and hawiian shirt. And his speech about fighting evil at the end was classic.
5)Dead Man's Party- Not the greatest episode ever, but gave a few funny moents, like Oz talking about the get together,shindig or hootinanny (alot of hoot with a little bit of nanny), and Buffy harrasing Jonothan at her party was funny also.
And as an added bonus
Funniest Characters on teh show:
1) Anya
2) Xander
3)Spike
4) Andrew
5)Cordelia
6)Jonothan
7)Oz
8)Wesley
9)The Mayor
10) Warren