When Jay breaks up with his girlfriend, series 1 I believe.
Will: Alright you big poof? Where's your bit then? I thought you'd be having it up to your nuts in guts
Jay: Nah, I had to er, I had to give her the boot
Will: Did you? I thought you were really into her
Then this line:
Jay: Nah, she was like frigid, and she wouldn't have this threesome even though I organised it with a top lezzer model, and (sobbing) my cock was too big for her