It's primarily British slang, though it caught on stateside in a lmited capacity 10-15 years ago, with the broadcast of, "The Young Ones," a Brit sit-com that was shown on, I think VH1 (?)
Of course, from now on, it will also be recognized as an euphemism for "Human Shield."
I'm not sure if you ever listen to Bob and Tom on the radio, but they have a skit that I used to like a lot. My favorite phrase from it was - "If you're not playing a Gibson and a Marshall - you're a bloody wanker."
Wanker...British term for spanking your monkey.
