Endearing Glasgow slang used to describe one who's actions and outlook verge on insanity, especially if you are in awe of said person. A compound of the words sick(ill) and nut(head)
Nickname for someone who is continually off work "sick", usually faking it because they are simply too lazy or irresponsible and can't be bothered to come in to work like the rest of us. Most of the time they don't even bother to call in with a reason.
An excessive reliance on the use of sick notes due to repeated illness/injury, to get out of going to school or going to work (e.g. playing professional football)