Why is the ninth month called September?
1940s, "masturbator," British slang, from wank "to masturbate," of unknown origin. General sense of "contemptible person" is attested from 1972. Cf. sense evolution of jerk (n.).
[origin unknown; perhaps fr British dialect wank, ''a violent blow,'' and semantically analogous with beat one's meat, whack off, pound one's peenie, etc]