An anime sock fetish is when people find pictures of anime girls (usually lolicon) wearing socks. Once the desired picture has been located.
It's not weird, its cute in a unique way. Personally I don't find feet fetishes weird or gross. So socks are just fine! I like wearing socks, they are really comfortable.
Why would you want to? Most people get aroused by overtly sexual scenes. If you can get arroused by innocuous covert things and it gets you off, good for you.
I've had a sock fetish for as long as I can remember, I believe it started as a young child because I can remember being fixated on and smelling my sister's.