Clubhouses is basically a perfect episode, i love all the roy scenes especially "now for the last time, go cut some firewood!".
gnomes is a really close number 2 for me, "step one: collect underpants, step three: profit". tweek is hillarious in this and i think the tweak family is my favorite family in south park.
my number 3 pick would have to be mexican staring frog because of the vietnam flashbacks, and if i could bring back 2 elements from early south park it would be jimbo and ned hunting trips, and jesus and pals, and this episode has both.
Season 2 is great!