When a girl gives a hand-job to a guy and then slaps his face with his cum still in her hand, spreading it all over his face - as a part of women's retaliation for all the
nasty sexual things men do to them so they can tell their
friends later (or write about it on
urban dictionary...).
"He acted like such a douche last night I had to
wet-
slap him. He got the wet slap alright."
"Girl, I can't believe you just
wet-slapped me!"