Today, on the bus, someone tried to open the rear doors in front of an icy snowbank. The doors are hydraulically-assisted (or maybe pneumatically, but anyhow, pressure-assisted!) so when you push on the handle the door opens for you. They got halfway open and hit the snowbank, but they were still pressurized so you couldn't pull them shut.
The driver took care of this -- and in retrospect I've seen this before but I didn't know what was going on -- by shutting down the bus, waiting for the doors to close, and starting the bus again. That's one hell of a failure mode.