Ray J put on a show for our “TMZ After Dark” tour riders Saturday night … no, it wasn’t a rap show, it was a striptease — ’cause he popped his shirt off!

The rapper joined us once again on the new tour — he’s our most regular celebrity rider so far — and, he gave the whole group an unforgettable experience … kicking off by showing everyone what it’s like to be the subject of paparazzi pics.

A whole bunch of paps shot Ray J through the door … and, he told the riders this is the life of a celeb in H’wood — before taking them around to some of the hottest spots in the area.

The crew stopped by Craig’s … where Ray J actually hopped off the bus to grab his buddy Gatsby Randolph — an artist with more than 1 million followers on Instagram.

Gatsby partied with the bus for a while before hopping off … but, Ray J kept the energy high with a series of bangers — before he removed his shirt and jumped out in Hollywood to dance on the street.