It's not supposed to happen, but it's not outrageously difficult to imagine how it could. Earlier this year I discovered that most garbage disposals are just sort of hanging in place, similar to the way you might see a jar hanging from a lid that's been nailed to the bottom of a shelf. Ideally the disposal has been rotated well away from the orientation in which it was first suspended, but that may require some wrestling with it, and it may feel like it's securely in place even if it's not.

This is not to excuse the installer in any way. Just that the disposal falling out is not quite as far-fetched as it would be if garbage disposals were bolted into place (as I once thought they were).

You can buy 1/2 hp garbage disposals at Home Depot for something like $70. Garbage disposal installation kits run about $10 and "include everything you need to install a garbage disposal!" Except for the bits not included.

If you think it's probably mostly the installer's fault then, um... good luck with the landlady, there.

The plumbing probably needs fixing, even if the disposal has somehow survived both the shotglass and the fall. Wait, did it break the plumbing, or just pull it down with it? What's stopping the water from running out all over your kitchen when you run the other side of the sink?

Ted: That’s reassuring. My first thought was, like, metal fatigue. (I wonder if the torque from the motor is supposed to contribute to keeping it rotated in the right direction, so that not using it would make it more vulnerable to working itself loose. Or not. I should probably just count myself lucky it didn’t fall while it was running and full of water.)

Jackie: It was luck, now it’s luck and Saran Wrap. It looks like the bit of PVC pipe from the disposal to the joint may not have actually been attached at the joint end, per se, to begin with.

I figure given the shot glass incident I’m on the hook for a new garbage disposal anyway.