(A) wanker

In British slang, a wanker is a pejorative term for someone who plays with himself or is a detestable person.
One example would be Giles Coren, a restaurant reviewer in England, who went ballistic on newspaper copy editors ("subs" as they're called) for removing the article "a" from one of his reviews.
He picks it up from here, in all his foul-mouthed, verbose petulance. At the end of the day, he has a point that the deletion of that single letter ruined a good double entendre. But, really Giles, is it worth vaulting yourself into the modern Pantheon of jackasses to make a point? I guess it is.

(Tip of the fountain pen to my old colleague Paul Dempsey for the article reference).