I have a couple scars on my knuckles because I have deep-seated problems with rage and I'm actually kinda ashamed of it, thankfully I live alone for most of the year so when I have outbursts there's usually nobody around to see it.
Some funny ones would be like when I slammed two sliding glass doors so hard the glass shattered, I wrestled a lamp to the ground as if it was a human being and shattered it all over the place (kek), and one time I punched through my bedroom door because somebody told me I should make an "egg sandwich"