This happened to me, but from catching myself when I fell skating.
It didn't hurt at all until I wondered why my wrist wouldn't rotate and looked down. I saw this, then it started to hurt.
The best part was the skating rink trying to get me to retroactively sign a liability waiver, and me telling them I broke my dominant arm (I didn't).
Well, the best part was the hospital refusing to set it, then the orthopedist refusing to belive the hospital didn't set it, so I had to have it surgically set a week later.