It is a sexual analogy meaning that you want to have sex/bang someone. It is a way of joking around and playing with someone telling them you want to hook up, but not making it obvious to the public.
Person 1: Bro I'm gonna go clean my toaster in the bathtub, will you go plug it in for me?
Person 2: I bet you play Russian Roulette with a glock
Person 1: What does that mean?
Person 2: It doesn't matter wheres the sparkplug
Holding someone's hands, and kissing their cheeks, but not going further, and making a dude really anxious for something to happen. Then you realize they are trying to play with your heart