A slang term of British origin meaning to masturbate. Usually used as a comedic alternative to "Beat your meat" or any variation of that slang.
Friend: Hey, what are you doing in there?!
You: Uh, just applying the handbrake, if you know what I mean.
Friend: Disgusting, dude.
You: Uh, just applying the handbrake, if you know what I mean.
Friend: Disgusting, dude.
by SwagLowMuffins June 2, 2014