OP said his combo didn't work so his friend just yanked the lock off. His board didn't actually get stolen. So few people use locks on the mountain that a would be thief would be stupid to try for the ones that do have locks. Move one board down and he's set. Ultimately, like bikes, a lock is never 100% secure. All they do is tell the thief there are easier targets.
That thing I do to escape the world and have fun with my friends