One time I came out of the gym to find that I had locked my keys in my car. I spent the next half hour angry that my two roommates weren't home to bring me my spare key. Eventually I gave up and walked home (nearly three miles round trip) to get my spare key, climbing through the window to get in. When I got back to the car and unlocked the door, I noticed the lock didn't click to unlock. The door was unlocked the whole time. I simply saw my keys on the passenger seat and assumed, never even tried to open the door. Probably the only time in 10 years of driving that I didn't lock my door outside of a garage.
My roommates saved the voicemails I left for audio proof that I'm a doofus.