if u want to gain mass quickly u need to lift heavy, and u need to eat a lot, obviously not junk foods but protein, carbs, and a lot of fruits and vegetables, no junk food, even when u think u are full, eat more.
keep ur hands up always protecting the head and keep ur chin tucked in so u dont get knocked the fuck out and just act ur like fuckin insane and he wont want to fight u, just go crazy and bang ur head on some garbage cans or somthing, it might scare him off