Jermaine Jones Musical Booking Agency is a location in L.A. Noire. You can find it in the Vice cases. It's got alot to do with the drug dealing concept and has a radio full of Army Surplus Morphine stolen from a marine ship in San Pedro.
They deal most of the drugs with Mickey Cohen and his men and then sell it on to the owner of The Black Caesar, who sells it to anyone who wants it on the bottom of popcorn cups. The main main drugs come from Mickey Cohen and are sold out all over LA, but where Jetmaine Jones gets them is a mystery.