There two kinds of people your never ever under any circumstances want to harass/assault/be an asshole to: Bouncers, and skater punks.

In both cases they can be your best friend or worst enemy depending on how well you treat them. I've had bouncers stand by while I bullied someone out of a bar since I was handling it firmly and calmly and the guy was being a drunken creep to one of my girl friends. I have also had a bouncer intervene on my behalf when some chuds outside tried to fuck with me while I was out smoking. I have never once had a bad interaction with a bouncer.

Hell the bouncer at my favorite local dive just pats me on the back and waves me in past the line when it's busy on a show night. Befriend your local bouncers folks.