I would say about 2 or 3 times a week, I arrive somewhere and think, "Wait, is today the right day?"  Last night I showed up at my Bible study on time, but no one was there (this is normal).  But then the lights were off in the house we were supposed to meet at, so I thought, "Wait, is today Thursday?  Did I miss something?"  It turns out the lights just happened to be out, and more people showed up later. 

This morning I got to work and it was nice and dark in my office area.  I'm perfectly fine with this because it lets me get a slow start to my day.  But it's after 9am now and I'm pretty sure no one else is here.  Is today Saturday or something?  Did they cancel work?  Am I missing something? 

This is similar to my fear of showing up in public places and forgetting to wear pants.