Yes. A few times on my road bikes. Once it was at a stop sign and I didn't get out fast enough. I wonder what I looked like to the pretty girl inside the car as my face slide down the passenger side window.

I have learned the hard way that I should never, ever, ever, ever ride clipless on my mountain bike if any trails are involved. After that day I felt like I'd gone 10 rounds with Muhammad Ali.
I'll use them if the ride is just dirt roads but if I know that I will be on any trails I switch over to platforms before the ride.