My wife fell down and has truly epic bruising and swelling on her knee and thereabouts. (Thereabouts being a foot or so from the knee...)
Abstract art! Such vivid colors! And it changes! Never the same image twice!
And, what's more, she can get another one for free anytime she wants one!
Just do a pratfall in some cat oocky-oocky, or walk into a glass door, or a host of other everyday activities. You don't even have to put wear and tear on your bicycle, you can get one in the comfort of your home.
There (ahem) might be some ancillary costs at the doctors, though...