In the Ballard of gay tony, get some sticky bombs and a parachute. Go to any high building and put a bunch of sticky bombs at the top. jump off the building and land using the parachute. When you land, make sure there are people around you. Then, blow up the bombs. the pedestrians will think you are a terrorist and start attacking you.
In Grand Theft Auto 3, on PC, type "nobody likes me" cheat, and all peds hate you.