Please help me to understand sentence '' You’re a gnat’s ass away from having this conversation behind bars.'' to in the following dialog in movie ''Headlock'' (about minute 26 to 27).
PETER TO TESS: Are you fucking kidding me?! You’re a gnat’s ass away from having this conversation behind bars. Do you realize that? Jesus Christ, Tess. What are you trying to accomplish here?
TESS TO PETER: What is this trying to accomplish, Peter.
PETER TO TESS: I’m following procedure! TESS TO PETER: Procedure? Don’t give me those company bullshit lines!