The first time I disassembled a 1911, I launched the spring cap past my face and into the ceiling. There is a divot in the plaster from where it hit. Now, that is what a true 1911 idiot mark is.
Oh, there was this other time I left the house with an empty holster. Damn did I feel like an idiot going out unarmed. The gun sat home that day in the safe while I did my best to conceal my stupidity.
I've caught myself leaving home with an empty holster once or twice. Not saying it can't happen again but the embarrassment of an unintentional GFZ protest has me double checking everything now:
1. Holster
2. Pistol
3. Spare mags
4. Knife
5. Flashlight
6. Keys
7. Cell phone
The thought of needing to draw and grabbing a handful of air is pretty damn scary.
EDIT: And the time I was grouse hunting up in Canada with my dad and missed a bird because I forgot to pull the hammer back (all caught on video for posterity). Shotgun was a single shot H&R .410.