I went for a shore dive at La Jolla Shores and forgot my mask, had to abort that dive, very disappointing to me and my buddy. For many years now I have used a net gear bag/backpack and pack everything in the same place, in nearly the same order. I haven't forgotten anything in a long time.
Over the years, I have jumped off the boat without my fins, without weight, and without turning my air on. I tried to jump in once without a mask on but someone asked me if I'd rather dive with one. I learned from these "embarrassing" events and have not repeated them for many years, but I'm sure I will.