I was at the checkout lane at my local grocery store when my debit card got declined. Not insufficient funds, not incorrect PIN, just... declined. With no explanation. I was lucky that my roommate, who I was shopping with, was willing to put my nearly $100 of groceries on her credit card, with me promising up and down that I would pay her back as soon as I got it all figured out.
Immediately, I went home and called my bank. After being on hold for 40 minutes, I was told that my debit card had been locked because they suspected it had been tampered with or otherwise compromised. That's fine, and I was glad they did that - but I got no notification. No email, no phone call, no letter, not even a notice when I logged in to my online account (which I'd done that morning to make sure I had the funds for groceries that day). I had to use my card, and have it declined, and then call them to find out they'd locked it.
It was just... frustrating. And then I had to wait almost 8 hours between the time that I set up a new PIN and I could actually access my money. So my friend who was coming in from out of town that night... yeah, I wouldn't have had any money had I not tried to go grocery shopping earlier in the day.