Having an absolutely soul-crushing embarrassing story is all apart of growing up, and if it hasn't happened to you yet, you should be very, very afraid.
Here's mine: Once I was on a public bus, on my way home, and there were a few people sitting behind me that also went to my school. Anyway, I could overhear them talking, and it sounded like they were talking badly about me behind my back. So I turned around and said "You know I can hear you, right?" in a very combative, sassy tone.
Turned out they weren't talking about me at all, and I just made a fool of myself. That was eight years ago, and I still think about it all the time.