Apparently it’s a Texas-specific drug that’s a combination of hydrocodone, alprazolam, and carisoprodol, aka an opioid, a benzo, and a muscle relaxant. It’s being churned out by Houston pill mills and sounds even more dangerous than “lean,” aka “sizzurp,” which is codeine-promethazine cough syrup with soda (and sometimes a Jolly Rancher), popularized by Houston rappers. Thanks to Dayong Lee for sending me her paper on the subject!
Looks like there's a Florida version too: https://www.sciencedirect.com/science/article/abs/pii/S0376871619304703
Here's the link to the paper: https://www.sciencedirect.com/science/article/abs/pii/S0379073821001390