A term i have personally created to define a group of vary large ghetto(or niggerish) looking black men, Who look like they will Molest or kill you.
If you say it about one single black man, it meens he looks like he had just recently gotten out of prison. Therefore you fear for your life and or virginity/innocence.
Robert: Hey Jim, "there are a bunch of bubba's" here, Lets leave
Jim: Way ahead of you, Man!
Conner: Check out that Bubba, Joey.
Joey: Dont look at him, just keep walking.