People have teased me about it for years. They ask me if I shave it. Or tell me that it's because I pull my socks too high... but I don't. I haven't worn anything but sandals for 7 years now and it's not coming back. I was thinking maybe it was because I rub my feet together when I sleep or something.

Does anyone know where I could find the name for this? I've met a couple other people with the problem as well.

Thanks!