One of hip-hop’s most ubiquitous but dangerous habits is at the center of a federal investigation, and popular figures Chris Brown and Lil Wayne could be involved.

According to The Miami Herald, federal authorities are investigating a $15,000 wire transfer from Brown to the bank account of Miami music producer Harrison Garcia last year, also known as “Muhammad-al-Lean.” The nickname references lean, or “sizzurp,” the popular but addictive cough syrup-and-soda drink made from mixing promethazine with codeine.

The 26-year-old Garcia is currently on trial where, on Thursday (April 6), jurors got to see a text message sent from the producer to a woman. The text message contained a screenshot of the $15,000 bank deposit from a “Christopher Brown” into his account. Garcia wrote, “Look who put money my account.”

The woman responded, “What that for LOL.” Garcia replied, “Drugs … lean and shit.”

Jurors also got to see text messages that seemingly confirmed Garcia ordering his “do-boy” to deliver drugs to Lil Wayne. “I’ll shoot u some tress; it’s for Wayne,” Garcia allegedly wrote.

A federal agent also testified that, when he was first arrested last October, Garcia bragged that he had sold “a lot of narcotics” to Wayne.