A nutcase. As in not right
in the head. Always have their shirt
tucked into their trousers which are half way up their chest.
A person who is most likely to come and regail you with stories in a pub of when they "Nutted this bloke" and how his helper is nicking money from him.
They vary in condition, some are worse than others, with
the worst ones not having control of bladder. A common hobbie of a Jellyhead is shouting at passing cars.
Best avoided