This is also a rhyme/game of the grade school persuasion, to be said when one needs to dispose of an apple core.
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!"
This rhyme tends to crop up in Warner Bros. cartoons from the 1940s. It will usually feature Bugs Bunny (as person A, considering his trickster god status in the early cartoons) and Elmer Fudd. When asked, "Who's your friend?", Elmer sometimes answers, "Me!", whereupon he is beaned smartly in the forehead.