Ray J‘s doesn’t skimp out on the SKIMS jokes on our “TMZ After Dark” tour … going into a full facetious meltdown when seeing Kim Kardashian‘s L.A. store.

The rapper took the helm of the tour bus with DJ Mike T of VOX DJs backing him up Saturday night … and, he cracked up the riders when passing the store — screaming and curling up into a ball while making a pun about SKIMS.

As you know … Ray J and Kim K used to date — he’s the dude from the now infamous sex tape — and, though he’s far removed from the relationship, it seems he still knows how to use his ex for an extra wisecrack here and there.

Ray J also loves to get to know the riders on our tour a bit … though he may want to stay far away from one he met this weekend — who showed off a tattoo of notorious serial killer Jeffrey Dahmer.

We never got to the bottom of why she’s got The Milwaukee Monster tattooed on her arm … but, Ray J certainly had no interest in finding out.

As always, there’s ton of drinks to go around at each place where the bus stops … and, Ray J ripped off his shirt at one point — pretty par for the course when he hosts the tour.

Ray J’s one of a few people to host the evening ride through Hollywood … with Chanel West Coast and Jerry O’Connell jumping up in the past as well. The DJs change as well — with DJ Trey Money playing music on Friday for the riders.

And, Ray J’s got some exciting news … announcing TMZ’s All-Out Brunch Party tour, coming soon.

If you’re looking for a late-night ride though, we’ve got you covered … ’cause TMZ is doubling the fun on Saturday nights with a second bus for “TMZ After Dark” due to overwhelming demand.