In a tv series or a movie a guy is playing guitar in a bar. He wrote a song about a girl who was going to come but didnt. Just before he starts singing he says something like 'Hey dont panic but i'm naked under these clothes.'
It's Postgrad! I was wondering too and searched it. Your description of the movie reminded me.
Hope you're set up with an email notification to get this response more than a year on.
Now you know, go on and live your life the best you can!