Apple Core, Baltimore

This is a game PawPaw used to play when he was a kid in the 1920s and early 1930s:

Person A has eaten an apple down to the core, while persons B and C look on.

A: "Apple core!"

B: "Baltimore!"

A: "Who's your friend?"

B: "Uh...Person C!"

A throws the gnawed apple core at C.

C: "Ow!"