One of GTA V's best characters, Franklin, was actually a boss in real life as well. The voice actor who plays Franklin in the game claims he knocked out Ice Cube back in the day, and even stole his chain.
Before he lent his voice to Franklin, Shawn Fonteno was a rapper named Solo. He describes an altercation he and Ice Cube had in the documentary "Beef 2," which ended with Cube getting knocked unconscious. It was a story big in the '90s, when Cube and Cypress Hill had their beef going on. Fonteno was tight with Cypress Hill, and that's how it all happened.
Source: hiphopwired.com
