During a show on April 30 in Aspen, Colo., a fan who was tossing money around in the crowd was pulled on stage by Pitbull. The guy then thought it would be a good idea to make it rain in Pit's face ... and was dead wrong.

Pitbull suddenly levels the guy -- repeat, LEVELS the guy -- with a devastating right hand, then follows it up with a Beckham-esque kick once the dude was on the ground.

We're told the fan was tossed out of the venue after getting socked -- but was let back in once he convinced security he meant no harm. Cops were never even called to the scene.

Either way, the best part of the whole thing: Pitbull never misses a beat when he knocks the dude flat.