face-high-five

Slapping someone and leaving your hand on their face for more than 1 second. Thus high fiving their face. If you remove your hand before 1 second has passed, you have slapped your friend and thus subjected yourself the a slap in return.

"Man you just slapped me!"
"No, I gave you a face-high-five. My hand stayed on your face for longer than 1 second."