It means you be lying. So like if you say something like I killed somebody yesterday and said later that you was fucking a hoe, someone you told that bullshit to, will say you be cappin
You: my side bitches Bianca and shonda'laquesha was getting fucked yesterday and this other side hoe showed up and I shot her.
Jon Jon: nigga you be cappin now stop lying before I take yo side bitches and yo momz
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."