So after seeing the other new gta4 glitch not just get thrown in the dirt, I figured I'd share this since I haven't found anything relating to it, so it may be new. Yay nostalgia.
- Find the bouncer to the Masonette 9 or Hercules bar (Masonette 9 will be on your map, Hercules is about one or two blocks north from there)
- Make the bouncer mad at you so they attack you.
- Make a policeman see him hit you and attempt an arrest
- The bouncer will fight back but it's invulnerable to everything that isn't caused by you
Note: he will still be mad at you and go after you if no policemen are presant.