Drug Dealer.
Ice Cream is the code used to refer to the drug that is being sold, code is Only really necessary over the phone or in a public place.
At the shops: "Man, I'm hella down to get sum ice-cream."
Reply: "Yeah, fo sheezee! let's ring the Ice Cream Man."
Phonecall: "Hey man whatzup? I'm Jus' keen to come round and get sum Ice-Cream off yo'"