One who is a physical stand-in for a sexual fantasy - a lookalike that one can whack off to while maintaining a fantasy of the original. The doppelganger is an innocent victim of your chudding tempest, by the way.
That poor girl. If she only knew that you stumbled across a porn lookalike ...
I was browsing some porn on the weekend, and I came across a complete doppelwhacker for my hot guidance counselor. I squeezed one out in less than a minute.
Your identical twin of a penis. Exactly the same dimensions, skin tone and "flaccid to hard" growth velocity. Similar to Joey from Friends hand twin, only it's your man-junk.
Everybody has one.
"This dick is your dick, this dick is my dick, oh wait , that's your dick, no wait it's my dick"