twonk

Noun

 * 1)  A stupid person.
 * 2) * 1985, Only Fools and Horses (TV series), "It's Only Rock and Roll" (episode)
 * You dozy little twonk, Rodney. You bang again on the roof of my van like that and it won't be Frankie Goes to Hollywood, it'll be Rodney goes to hospital.
 * 1)  Nonsense; rubbish.
 * What twonk you are talking!
 * What twonk you are talking!

Etymology 2
Possibly onomatopoeic

Verb

 * 1)  To hit or slap.