I've been having these thoughts lately that I'd read a book where one of the characters (a lowborn) pretended to be a knight so that they could compete in the tournaments. This character would win almost every tournament, and was highly feared. I don't know how reliable my memory is about this, but I think he was a frog, or became a frog, or had armor that looked like a frog, or something to do with frogs. No one knows his true identity, save maybe a cousin or sister, I can't remember. I truly wish I'd had more information, but this is all I've got to go on. If I'm right, I read this book in the last 3 years. Sadly, this is the only memorable thing about it. But I can't get it out of my head.
Now that I'm thinking about it, the knight also yelled at other knights. Don't remember why, but he didn't reveal himself during this. Just yelled at them for something.