1. A rebel with a cause, especially an anti-authoritarian cause
2. An activist with the Bureaucrash Foundation.
1. He's a real crasher when it comes to defacing parking meters.
2. Did you hear about what the Crashers did in Cancun?
1.Someone who waits till the last moment to do anything.
3.From the word crash(to sleep) someone who is too lazy to go home when it's late, and sleeps wherever he is.
Paul: At this time yesterday John had nothing prepared for the presentation but he still gave a wonderful presentation this morning.
Anne: Yeah, John's a crasher.