An acronym standing for "Hard Body Mafia," which is quite possibly the best Xbox Livegang on "Saints Row 2." You will know when you see us because we tend to wear all-blue clothing. When you see a gang of all-blue, that means you better tuck your head between your legs and run like a bitch because you're about to get pwned with shotties, AK's, and rocket launchers.
"Saints Row 2" Newb: "Oh shit! Who is that gang on the rival team all decked out in blue?!"
"Saints Row 2" Vet: "That'd be HBM...one of the baddest mothafucking gangs on here! You better get outta here newb!"