Stupid Submariner Tricks

One time when I was a JO, I went on leave with the reactor safety keys. I'd gotten relieved as EDO and signed out on leave, and drove home without turning over the keys. When I got home, I heard the phone ringing inside, and as I reached into my pocket to get the keys, I felt the lanyard and thought, "I bet I know what that call's about." (There was an RC entry planned for that day). Had to turn around and head back to the boat.

What's the most embarrassing gaffe you've ever committed on a submarine?