What does this slang mean?

[liveyourlife]

I put a pic of me shooting at the shooting range with an assault rifle (on Facebook). My friend commented "B b BAMF." What does that mean?
I feel too dumb asking him haha
Thank you!
haha what's Bb though?

[Nelson]

" be large, be small, be alert my friend".

[Jayson Liao]

bamf means bad a*s mother f*cker, DON'T REPORT ME PLZ I WAS ANSWERING A QUESTION! Btw, its the truth, bb means be back, big brother, or the standard size of a lead pellet used for those air rifles

[Aaliyah]

Bad Ass Mother F***er
you could look up slang words on here if you don't know what they mean http://internetslang.com/

[Daisy]

bad a*** mofo