My youngest has discovered name-calling. (Sigh)
When he is trying to push someone's buttons: "You poopy cat!"
When someone has swiped his toast: "You knuckle-butt!" (I think this is an amalgamation of two phrases he saw in different shows; "monkey butt" and "knuckle head".)
When he is attempting cheerful banter: "You bucko" (from the third Ice Age movie).
When he really wants to start something, "You toopid poopy cat knuckle butt!"
When he is hurt: "You BABY! You in bi' trubbow!"
I usually reserve the hot sauce for the adult bad words but I may have to get a little more strict with this one.