When (mainly males) (unless you be a tranny) are totally naked and do circle movements with their hips so that they get their genitalia swinging round and round in almost-perfect circles. This action is usually done in front of a mirror: it can be very entertaining for guys ya know.
Guy1: Dude, you know that film 'Bruno'?
Guy2: like, who doesn't?
Guy1: yeah, i love the part where he flops his cock out and starts willy wanging.
Guy2: are you bent?
This phrase means to "masturbate". As a snake is long, skinny and rounded like a penis. And wrangling means to tend or round up, which is what your are doing to the snake or your penis.
Guy 1: Hey girl mind wrangling the snake.
Female Snake Enthusiast: Wow really. Sure I'll do it, where is it at?
Guy 1: *whips out penis* Get to wrangling!