We had a guy almost die in an AirTran cargo bin after falling asleep. The aft bin was unpressurized, and the rampers frequently took a nap back there waiting on the bags. One guy apparently fell asleep and they closed the door on him. As they were taxiing out for takeoff, he woke up and realized that he was in an unpressurized bin and panicked. He started banging on the wall hoping someone would hear him, but then he did something stupid: he lit a cigarette and held it up to the smoke detector to get it to go off, thinking that the crew would pay attention to it when the message popped up in the cockpit. Only problem is that the crew definitely paid attention, and they were about to blow the halon bottles when the aft FA called up and said she heard someone banging on the wall. Had she called a few seconds later, that would have been a suffocated ramper.
Moral of the story: if you're a ramper trapped in a cargo bin, don't try to set off the smoke detector to get attention. You'll probably die.