Series 3, Episode 9
It's Thanksgiving and the boys are more intent on watching the football on tv than they are in their food, so the gang get together to have a 3x3 football game in their back yard. What starts out as a bit of fun turns competitive (and almost down right nasty) when Chandler and Joey both attempt to catch the attention of a beautiful Dutch bystander and Ross & Monica refuse to back down from one another.
An absolutely brilliant episode which has some really funny moments, nonemoreso than when Phoebe flashes her boobs at Chandler to distract him (unfortunately she has her back to the camera) and he ends up in a bush. Priceless.