Your go to guy for your dick encounters of the sleazy variety. It's not the guy you try to date, its just the guy you call when you want some immediate satisfaction.
It's 2am and I'm drunk and horny, let me call my benedick!!
Like the American General who betrayed the colonies but was ultimately caught, this person is a friend or acquaintance who runs their mouth or betrays you but is caught by you.
Emphasize the dick on it like a Bene-DICK