I have a recurring "random" injury. I call it random because I have no idea how it came to be. I call it recurring because it seems to recur, in the same place, and with the same degree of healing. It is on my forehead, right in the middle, and at the top, where my hair meets my ... non-haired part. It is a small scar, and when it "appears", it's always semi-healed. But it's scabbed over, indicating blood came out at some point.
I think I've been abducted by aliens, and they opened up my brain, did some stuff, then closed it and sent me back.