1. slang An ambulance, especially on its way to a gruesome incident. I had to sit there and hold my own guts in place while we waited for a meat wagon to arrive. They loaded up the poor guy into the meat wagon, his leg barely attached to his body anymore.

2. slang Any vehicle, such as that of a coroner, used to transport a dead body from some place to a morgue. Police set up a barrier around the area until a meat wagon could come and collect the body.