From the Dogspotting Facebook group wherein people post pictures of unexpected encounters with excellent canines.
Same idea, with a twist. To wit:
I gathered acquaintances, friends both casual and close, paired them randomly, put them in a void, and asked them to hit each other in the face. No one was pressured, and everyone was hit as hard as THEY asked to be hit.
UPDATE: A classy Max Landis gives the haters what they want.
(Thanks Darren Cleary)