It is when a male takes a shit in the mouths of multiple girls at the same time - as they lie side by side in a row. It is also a symbolic gesture against current US foreign policies. This was perfected by an individual named Brandon at an Anti-War rally, and thus his initials are represented in the name.
All them bitches were lined up for a BL Bomber!
Damn, looks like Iraq is getting a BL Bomber!