Me? I've never done anything embarassing in my life.
One time I did spot a lady about to re-enter the dining room after a trip to the restroom, we were both out in the empty corrider just outside the main doors. How did I know she had just been to the restroom? The back of her skirt was tucked into the waistband of her pantyhose.
I cleared my throat loudly and when she looked at me I turned around and pointed at my back - she just started at me like I was crazy - she obviously didn't have a clue! So I said, "your dress is caught." and she said "oh' and then she felt back there and then said, "OOOhHHHHHH!"
She thanked me profusely.