A sexual act, performed to humiliate another, usually a woman. The man shaves his pubic hair, leaving it until he ejaculates in the females face, then throws the hair into her face where it sticks and shouts "monkeyface!". Alternatively the man may decide to rip his or his partner's pubic hair out at the moment of passion and throw it into the mixer.
"Upon sighting the White Whale, Captain Ahab grabbed Queeqeg and forced him roughly to his knees where he gave him a monkeyfacing, in the New England style". From Moby Dick by Herman Melville.
Before sex, both participators shave each others pubic hair off. When the male reaches the moment of climax, spunks over the woman's face then proceeds to throw the pubes over said woman so they stick. Thus rendering the woman 'monkey faced'.