Here are some fun novelty socks!
These socks are "3D Socks", because they have pop out or flap out parts. In this case, it's Sonic's spikes! They're a pair of felt flat strips that are sewn to the back of the leg-area of the sock & stand out while you wear them. The socks are all blue & have classic style forward facing Sonic faces on the fronts (to make the gimmick make sense on the back) These are for teens or adults so anyone can wear them. These designers are really thinking: they've put the design up high enough that it won't be covered by most shoes. Too many designs just go on the foot, where it is never seen. Where can you find these silly fun socks?

In the gallary is a picture of what seems to be the same pair of socks
These are a Spencers' Gifts item that should be about 9.99 for a pair in the summer 2017 season. These are a fun, adult size (so, should fit any feet) pair of wacky socks if you didn't already have something super similar.