Something I learned as a bouncer. Kinda looks like the "calm down" gesture, but in reality all you gotta do is ball your fists and you're in fighting position. And with palms out, it doesn't look aggressive like getting into a fighting stance. Talk your shit like that, and as soon as dude lunges you're ready AND you have an out (you were just trying to calm dude down or whatever).

I used to do this with drunk assholes that had to go so that I could grab them in an instant, but not tip them off that I'm about to get aggressive.