Father Ted- There's too many but I think 'Speed 3'.
The IT Crowd- 'The Work Outing', although there are a few episodes from the third series which are up there.
Not Going Out- I think the 'Death' episode from series one, although again there are too many good gags in each of episode to choose
Spaced- The one with the shoot out the end (can't remember the name now!)
Friends- 'The one where nobody's ready' or that one where Ross makes up a Quiz and they end up swapping apartments
Gavin and Stacey- The one with the barn dance
Black Books- 'Grapes of Wrath', when Bernard and Manny make their own wine
Garth Marenghi's Darkplace- 'Skipper the Eyechild'
Extras- The one with Sir Ian McKellan
I'm Alan Partridge- The episode with 'DAN!!'
Phoenix Nights- When they have a family fun day