They were a gang at the turn of the century that gotjealous of men with pretty women and then when they saw someone rich they would come up to them and spit on them.
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.
I couldn't help getting a larrikin's hat every time I looked at it.
Rogue, Australian personality, Bush person. Marked by enthusiasm, passion, and Zest for life. Living life to the fullest extent possible. "100 miles a minute"