n. Another name for penis or cock. It is a term more often used to suggest the penis as a flute, irish tin whistle, or kazoo. It can also be refered to as a game, sexual in nature.
"What did I tell you about being a penis whistle?"
"Hey baby, lets get drunk later and play penis whistle..."
"I'm gonna make you play 'Oh Danny Boy' on my penis whistle if you don't shut up!"
Something they must have had in the 40's and 50's. As far as I know, a pennywhistle would be an old fashion term for "a whistle that costs a penny". Go figure. A moonpie would just be a somewhat archaic term for a pie shaped like the moon (circular).