I learned to really take a look at the time before you rush out of your apartment and head to work, because your alarm could have gone off 3 hours early for some, unknown by you, reason, and you could arrive to work with no one there, then stupidly realize what you did and then go back home and go back to bed, only to sleep for another two hours before getting up again.
It happens, yes. =/
In my defense, I've only been sleeping 2-3 hours a night all week, so I'm pretty sure I was hallucinating when I checked the time both when I shut my alarm clock off and also thought I was going to be late, because I normally leave 20 to and it was 15 to. But yeah, it was an interesting morning, needless to say. Lawlz..