Who is Psycho Loco (a.k.a. Juan Julio Sanchez) from The White Boy Shuffle and what is their importance?

Psycho Loco, also known as Juan Julio Sanchez, is legendary in Gunnar's neighborhood for his violent tendencies. Psycho's reputation is well deserved, and he is a member of the Gun Totin Hooligans gang. Psycho also goes onto become one of Gunnar's closest and trusted friends.