Okay, so I've been playing through San Andreas (the PSN version) and after completing the Stowaway mission. I was gliding high up, above that Cluckin' Bell in Tierra Robada, the one on that intersection.
Anyway as I did, I noticed a yellow arrow in the sky, I glided through it to see what would happen and basically CJ went in to this purplish vortex warp thing and about six parachuting CJs came on the screen, then it went back to normal and I couldn't get to the entrance marker anymore.
Any one else found this??