I remember watching this short film a while back. I don't recall from where I had heard about it, but it sure remained in my mind since them. It's called Inside. Directed by Trevor Sands with Jeremy Sisto as the lead.
I've actually enjoyed many of Jeremy Sisto's performances. He's a really good actor. Last I recall, he was in one of those Law & Order shows. Which one it is, I don't know. The film is 5 minutes and very well made. A simple and effective story with a clever ending. Enjoy!