Someone who consistently leaves a room without anyone noticing. This usually happens in a party/drinking scenario, and is usually because the person is weak. They know if they try to say goodbye they will be talked into staying/drinking for longer. So instead they find the perfect moment to sneak out quietly while everyone is distracted.
Sometimes they may also trick people by pretending they are going to the bathroom. And then they never return.
Hey what happened to you lastnight Steve? You completely smoke bombed! You're such a smoke bomber..