Cleaning up an repairing their own mess would probably have the most impact on these guys. At our school we caught some taggers who were vandalizing our school and the dean of students made them clean up their mess. It appeared very quickly that there were even more taggers than we caught because the ones doing the cleanup were so pissed off at cleaning up their friend's mess as well as their own that they ratted out the other guys. The next day the cleanup crew doubled in size as the other guys were put to work. The dean withheld 5 hours of community service from each one saying "that if there is any more tagging at school this year YOU will be cleaning it up" For the rest of the school year we didn't have a mark of tagging.
Now our school district calls cleanup 'corporal punishment' and we can't assign it, and GUESS WHAT HAPPENED........