This is Oscar doing his "Jabba the hut" imitation. Oscar really does have a neck but sometimes he likes to scrunch his head down into his shoulders so he can look plump and strange. He's a big Star Wars fan.
Boo is a cat with discriminating taste. He has a few close friends and he likes it that way. He's a very sweet cat but only when he wants to be. You don't want to mess with Boo!