A symbol tee....
But it's lumped in with the 'Valentine' items at the Sega Shop online in 2019. This one's title is "I Heart Sonic", and it's appropriate, if a bit abstract. The letter "I", a red pixelated heart shape, and the silouette all-blue Sonic face make up the 'slogan'. There's a row of red chaos emeralds below the whole design.
This isn't particularly a "Subtle-Sonic" item, because the face is clearly him, and everything's really big. The idea is ok, but the shirt somehow doesn't seem particularly cool? It broadcasts a message (probably) but it's not like 'wow that is neat', or particularly bringing in a fun new design. It is buyable in 2019 online for about 20 dollars in adults sizes.