A cross between a spiderman, and a donkeypunch...
So you're having anal sex. Just before you cum, you (the giver), punch the reciever in the back of the head. Their ass muscles tighten, increasing the sensation. Cum once inside, then quickly pull out and
nut in your hand. The reciever
will turn around, and as they do, slap them across the face with your
man go, whilst screaming "Go Web, Go!". Finally, adopt your finest superhero pose, and don't move until you're finished soaking up the
glory