I had a super bad one over the summer. I was going to go in for surgery cause I was sick of having it hurt, but a 3/4" sheet of 4'x8' MDF was dropped on it, vertically, while I was wearing sandals (because shoes hurt and I was trying to let my toe air out before you start about wearing sandals while doing carpentry). Nearly broke my toe, but it certainly took care of the nail, I killed it and the nail bed from the resulting damage, nail is still not fully back after 8 months.
TLRD: Just drop something heavy on your toe and lose the nail completely.