It's Friday, May 1st - the last day of classes - and you aren't wearing any pants. You leave your dorm and several people do a double-take as you head to the bus stop.
The driver laughs at you and asks if you're cold. "What do you mean?" you respond. He points out that you aren't wearing pants. "How about that..." you mutter. "I must have forgotten them."
You exit the bus and enter your first class. Your professor looks at you strangely, and mentions that you aren't the first person he's seen without pants on. You insist that you forgot your pants at home, and you have no idea why the other people aren't wearing pants. At any rate, you think it's a strange coincidence.