Here are Sonic "Slipper Socks" but only for little kids. Look at the proportion, they're not likely to fit many people. They're classic style, with Sonic faces & rings scattered over a gray background. The paper tag has 'collectors edition' (but why? it's a bit nonsense) Where are these sold?
The material is 'fleecy' for the bottom interior, there are rubberized bumper-dots for the less-slip sole & the upper part is made out of what feels like pajamas cloth type material. These are likely to be inexpensive, but they're also likely to not last that long or be super quality item either.