wet dreams make cum

Mondegreen of "What Dreams May Come", a 1998 American fantasy drama film, starring Robin Williams and Cuba Gooding Jr. Unsurprisingly it is also the name of a pornographic film. Be careful not to confuse them.

(over phone)

Person 1: I saw What Dreams May Come last night, it made me cry.
Person 2: Wet dreams make cum? It made me blow!