A coslap is what happens when a boy and a girl are making out but they don't want to have sex, so the boy pauses to ejaculate into a condom. He then slaps the girl with the condom full of his essence and they laugh and continue making out.
Boy: Whoa hold on a second! (ejaculates into condom)
Girl: Hey, what are you gonna do with that?
Boy: (coslaps her) Haha! You got coslapped!
Girl: Haha!
by IndieSnob June 5, 2006
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