Was at an FTO station and the FTO had brought the monitor in to do training with a third crew member. We got sent on standby and were 1/2 way across town when we got a call. Monitor was left on the training mannequin. Wasn't doing him or our patient much good there. Lucky it was a diabetic who came right around with dextrose. Ooops. Gotta love that feeling when you open the back doors and what you need isn't there!