Willy-Whacker

A penis that packs quite a punch, and by punch, I mean a big dick slap to the face of your enemy (Or partner, if she/he prefers it).

To give your partner a "Willy-Whacker" is to basically get an erection that is hard enough to whack the shit out of your partner.
Just swing it to one side and knock that bitch out.

Kyle: Dude, did you just knock your girlfriend out last night?
Nathan: Yeah, I gave Gina the Willy-Whacker.

Wicky-Whacker

A penis. Specifically, the type that is long and hard enough to slap someone across the face.

Brenda got slapped across the face by John's wicky-whacker.