Terminology used by low-life to describe their pistol. When one gang member asks another "where's wifey", you know it's time to leave because they are referring to the location of their gun and not their wife or ho or both.
Hey Hank, where's wifey? It's time to do that Spencer dude from the show the Hills, he's such a Nancy. While we're at it, let's give him a wedgie and a haircut!