Answer: Donkey Kong
This came up during one of the lunch room scenes when Billy was in elementary school. One of the little kids remarked that he thought "Mortal Kombat" on Sega Genesis was the best game ever, and Billy politely disagreed, saying that "Mortal Kombat" was a very good game, but that he thought "Donkey Kong" was the best. The kid told Billy that "Donkey Kong" sucked, and Billy got upset and yelled, "You know something, you suck!"