I kicked myself last week in Sainsbury's. About £20 worth of shopping had gone thru the till. But my card(s) were nowhere to be seen. I'd taken them with me to the local shop the previous evening, and instead of putting them back in my purse as I always do, I'd put them in my jacket pocket...doh! That included my savings card so I couldn't even get some cash out.
Luckily I had cash on me, but I felt mortified digging out every last bit of change.
My never-not-do ritual is to always make sure my keys are in my hand as I shut the front door...that can be an expensive mistake.