A trick to decieve your friends to get something that you want, though you may or may not deserve it. Or slyly doing something out of the view of your friends to get away with having to do more work.
Given the name from Peter Kay's "Uncle Knobhead"
similar to being two faced
1) Going to a party and laying ur coat on a bed to signify thats where ur staying.
2) Nagging someones head to make them tell you if they like you or not, and when they finally answer you, you shag their friends.
3) Telling your friend your going to the shop to get something, whilst really your goin meeting his/her ex-boy/girlfriend
4) Makin a brew at your mates house n not makin them one.