The bathrooms here at work have motion sensor lights, so when no one has been in the bathroom for a while the lights turn off. That's really important to know for the story.
So I walk in the bathroom and the lights are off. Upon my entry they turn on, and I go about my business. When my toilet flushes I hear some stirring. THERE WAS A GUY IN THE STALL THE WHOLE TIME I WAS IN THERE! I think he fell asleep on the toilet.