1. To become enraged, especially in a physically aggressive or imposing manner. A reference to The Incredible Hulk, a comic book character known for becoming very large and destructive when made angry. The bouncer finally hulked out on the dude after he told him for the third time to get out of the bar.
2. To perform some feat of extreme physical strength. I'll never forget seeing a 70-year-old granny hulking out and lifting the whole rear end of a car that had pinned her grandson to the ground.
3. To become very muscular, especially due to weightlifting. I was tired of being teased for how skinny I was, so I decided to spend the entire summer hulking out before the next school year started.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.