Literally only once in my entire life.

I worked at a major restaurant chain for a few years about a decade ago. One of our specialty bar drinks was a frozen strawberry banana daiquiri thing that was made with real bananas. One day, our bartender was mixing like five of these things for a big group. The bananas were cut in half in the morning for portioning and kept in a cooler until needed, where the half would be peeled and used. One of the bananas got peeled, put in the blender, and the half peel was tossed into the trash can with the others. Or so she thought.

She hands out the frozen drinks, then quickly steps away to go check on something else, walks past the trash can, and slips on a banana peel that didn't quite make it into the trash. We were busy, so many customers and a few servers saw.

She didn't get hurt. She mostly caught herself before hitting the ground. But for the rest of the time I worked there, we would poke fun at her for tripping on a banana peel that she put there.