This is old, but too good not to post:
Australian Ninjas chase off muggers
This is not too surprising. Dojos tend to be located where rents are really cheap, and that often means the bad part of town.
I can imagine the scene: Three guys start mugging the tourist on a dark alley. One ninja lurks in the shadows, spots the attack, then goes for reinforcements. The muggers see something out of the corner of their eye, then they see five shadowy shapes looming out of the darkness and rushing toward them. The shapes resolve into ninjas, and the muggers go running off.