To defecate on ones chest then hammer-punching it in a downward motion, causing it to explode and spread all over the individuals body and face, while breaking ones chest cavity, then immediately running out of the house.
The full phrase is "Stop! Hammertime!" but I'm a lousy conformist, so I put it here. It is by far the most awesome phrase ever. You could make Slimer from Ghostbusters say it and it would still make sense. Its inventor was nothing short of genius as well.