1. A common utterance attributed to the Marvel Comics shapechanger Bruce Banner a.k.a. the Incredible Hulk. Generally(see: always) heard when Banner is angered and has transformed into the aforementioned destructive green giant.
2. A rousing ejaculation emitted before summarily destroying everything and everyone in sight.

The Hulk Smash is an epic sexual maneuver. When a man is having sex (or getting head, but it works much better when having sex, as it's easier to conceal the green paint), he stops, pulls out, and dips his dick in a can of green paint. He then goes over to the head of the bed and bellows, "HULK SMASH" while cock-slapping the girl, from left to right, across her face. He then yells, "HULK SMASH" a second time, cock-smacking her on the backswing. He then yells, "HULK SMASH" a third and final time, knocking the lamp off of the night table. He gets five bonus points for breaking her jaw, and wins if he breaks her neck.

Note: There is an optional beginning to the Hulk Smash, where when the man gets his erection, he may say, "Bruce Banner's getting angry!!!". However, this beginning is only recommended for experienced Hulk Smashers.
Norm was undefeated because no one ever survived his Hulk Smashes.

The act of slamming both fists (hammer fist style) down on a woman's ass cheeks as you climax while having sex doggy style.

When a man ejaculates onto his fist and punches a Man/Woman in the face

The Sexual Act of hiding an equipped "hulk smash hand" toy under the covers. When the woman comes to bed, the man proceeds to say, "Make me a sammich." If the woman denies, the man proceeds with, "You wouldn't like me when I'm angry." At this point before she can walk away in disgust, the man gets up and bellows, "HULK SMAAAASH!!" while proceeding to grab her by the hair and shove the gigantic green hulk toy fist glove into her vagina repeatedly until she is as loose as a physically possible.

A sexual act in which the man ejaculates onto his fist, and after doing so punches the sexual partner in the face and yells repeditally " HULK SMASH GRRRRRR"

While performing anal sex on a girl, the guy pulls his dick out and punches the girl directly in the asshole inserting his fist. The act is not complete until the man exclaims: "Hulk Smash".