Here are 2 pairs of old Sonic House-Slippers.
These are actually more like 'house-shoes' as they are quite shoe-like in structure with elastic curves toward the top and no extra elements. One pair is red and blue, the other red and black. Each pair features Sonic doing a type of odd-looking punching gesture, with one fist in perspective. It's kind of strange they would choose such similar poses for similar pairs of slippers. The design is a type of tough plastic material that isn't shiny.