Back in my younger days, a lesbian literally had my back and saved my ass from getting stabbed. We were both bouncers, so it wasn't unusual for one of us to keep the other out of the hospital like that, though there were a few times one or both of us did despite our best efforts.
Which is way off topic, but the turn of phrase always reminds me of her. That lady was all of 5'3", and fought like a pissed off bulldog (which was her nickname), and she was more than willing to stand back to back with any of us, no matter how ugly things got.