When I fly down to California to work with my partners, the restroom down the hall from their offices has a motion sensor to turn the lights on and off.
It works great when you walk in, and does fine if you are just washing your hands, checking your hair or have a quick pee. But anything more than that, and the damn thing snaps off, leaving you in total darkness.
Of course, you can sit there in the dark waving your arms wildly around and eventually it will get the message and snap back on - bur only long enough to get back to business. No sooner has everything settled down enough to continue, but it snaps off again!
At first, I tried cursing at it, but found (not surprising for a motion detector) that it responds best to crude gestures.
Eventually, you just settle into an ongoing game with the wretched thing of waving and clenching until the job is done or the urge passes.