Vag smack
A quick smack to the vagina with the tips or knuckles of your fingers, much like the nut tap...
"This girl was messing with me, and I didn't want to get my make up messed up, so I vag smacked her"
Vag Smack of Death
A more extreme version of the "wet willy", when an offended woman takes her hand and wipes it on her wet vag. She then proceeds to pull her hand out of her pants and slap the offender with her vag-juice covered hand.
When Tina called me a dirty whore, I proceeded to give her the Vag Smack of Death.