Somebody who is deceptive, ignorant or otherwise unpleasantly cunning. Not a friendly, jovial term, a Sackhead is very much similar to a dickhead, in which said person is claimed to have a penis, or in this case a (Nut)'Sack' upon their head.
'Matt is a Sackhead'
'Only a Sackhead would do that'
'Only a Sackhead would do that'
by Mightybear April 11, 2006