Aussie rhyming slang for fat, as in erection. A larrikin is a lovable hooligan; a hat is something worn on the head.
by Sheepshagger July 26, 2006
Australian rhyming slang used to describe a male getting so excited over something or someone that he gets an erection, or fat. A larrikin is a likeable rogue while an erect penis resembles a hat, hence the term larrikin's hat.
by wardswords November 25, 2016