to be a bad-ass mofo, what would you choose and why? Only one choice!

I'm considering taking something...boxing, muay thai, jiu jitsu, karate, etc...but can't make up my mind. I'm looking for great self defence skills and the ability to kick ass when I need to bail out my drunk buddies in a barfight! But most of all I just want to get out of the house before the wife puts me to more work!

Thanks