This one is from a few decades back - I was 16, and out on my first ride with a brand new pair of Look clipless pedals (it was 1986 or so, they were the then fancy pants new black ones) and had rolled up to a stop light which was red. I was sitting through the light, minding my own business, when a convertable full of very cute girls pulled up beside me. I did not mind that at all. They kept staring at me. I looked back. Eventually, I realized that they were staring at me not because of the ego boosting "lookit that fit cyclist" reason but because I had completely forgotten to put my feet down and was balanced there in an unintentional trackstand. I wish I had not noticed this because, naturally enough, as soon as I realized that, I desperately wanted to put my foot down and of course couldn't as it was my first ride with the new pedals.
What happened next is predictable.
I went down like a felled tree.
All the girls gasped, looked over the side of the car, and asked if I was ok.
I was of course. I just wished that the ground would do me a favour and open up and swallow me whole. As it was, I lay there struggling with the pedals until the light went green and they left.