Here is a pair of Sonic slipper-socks.
These are a thick and warm sock meant to be worn around the house instead of a full house-slipper. They go up past the ankle, and have a stretchy top. The pattern in this case, is on the bottom, because it doubles as the 'traction' since they have no soles. In this case it's getting ready to run stock-Sonic among some stars and the logo. Why is it that odd greenish-yellow color? Becaue they're meant to glow in the dark!
Could this be the first glowing Sonic item discovered? (though the socks themselves are rather older, likely mid 1990s)