Amy, Rachel's other sister is a Pandora's box of laughter. Her immaturity, lack of regard for other people's feelings all wind up forming such a tight pack of laughter that make your lungs pop. The one liners and phrases like "crazy plate lady" or Amy's blatant description of Ross and Monica are purely hilarious.
Every punch in this episode cackles you up. This is one of the rare episodes in the history of World Television where the whole comedy surrounding the characters connect and there are no tributaries to the mainstream and yet they pull off a closed and neatly knit script and manage to make their audience laugh, and that very well. Easily one of the best episodes of the legendary show FRIENDS.