50 Cent -- Find Me In Da Fight Club (VIDEO)

50 Cent stepped inside a real life fight club, jumped in the ring ... and then got the joint hyped for a night of knockouts.

50 gave fans and fighters a pep talk before performing Tuesday night at BX Fight Club -- a genuine, underground fight club in the Bronx. The club encourages locals to put on the gloves and get their aggression out in the ring, instead of on the street with guns.

One of the owners, BX Hova, says the plan is to keep kids out of trouble. His pal Fif kicked off the night with "What Up Gangsta?"