To be a 'hotman' refers to outlandish behaviour by a person in the spirit of the Indonesian lawyer Hotman Paris Hutapea. Hutapea was once the lawyer for convicted Australian drug trafficker Schapelle Corby (pro bono). He left Corby in able to make money to afford a new Ferrari. He was also tried to take a gun into a meeting with an Australian government official.
"I can't believe you said that! You're a hotman!"
"What a hotman thing to do!" - to refer to a stupid act