To hit an ejaculating penis upon an object or person. Usually done by a man upon a woman.
Steve sperm whacked Donna.

Terri was sperm whacking Lisa with Roger's pud.
by Caesar Anonymous IV November 17, 2010
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The act of hitting an ejaculating penis upon an object or person. Usually by a man upon a woman.
Walter gave Mary a sperm whack between her cleavage.
by Caesar Anonymous IV November 17, 2010
Get the Sperm whack mug.