I may be wrong but I've always been under the impression that the term "wanking" or "wanker", is more of a British term than it is American. To call someone a wanker over here in the UK is generally considered to be a term of abuse and, although I definitely consider myself to be a "wanker", I mean it in the true sense of the word - ie: someone who masturbates a lot!
But I agree with what everyone else has said, it still feels great, whatever you call it!