Dependant on tone and context, knobshank can be used as a friendly or unfriendly term to insult someone who may have done something, or simply is, stupid.
Friendly: 'I can't believe how drunk you got, you knobshank.'
Unfriendly: 'That guy is a complete knobshank.'
Unfriendly: 'That guy is a complete knobshank.'
by Bob November 01, 2004
by Jimmybay May 31, 2003