It's an old joke, but perfectly executed as a running gag in this Budweiser spot. As the couple sit on the couch, the boyfriend asks where his girlfriend got the "huge" baggy T-shirt from. She says it was her ex-boyfriend's. "He must have been huge", the new boyfriend asks. Not taking the hint the girl says "yeah, he was". The new beau then suggests she wears one of his. "Nah, yours are kind of small", which sets up several other size-related gags with the girl oblivious to her boyfriends growing discomfort -- apparently.