"Dye Hard Fan" Sega Dreamcast promotional shirt. This was a UK giveaway for the system launch. You can see the "Tween" shillouette Sonic, that is the transition between old style, and SA style Sonics.
Here's a curious one. An analysis of Sonic! Here he is with various charts, stats and even a partial wire-frame mockup. This is a rather classy and unusual older shirt. It is difficult to run across...but interesting!
Strappy undershirt. From the 'short and stubby' days of Sonic, which are thankfully over. The background has an all-over print which gives the shirt a more quality feel, and makes it nearly impossible to bootleg. Not exactly sure -where- anyone could wear this, but oh well.
Uh oh. You'd best not wear this shirt around any gutterminds! The slogan is "Turn Me On" with some nice arrows and a logo. Of course, Sonic's face is in a "TV" for a supposedly cute effect, but the double meaning of the fraze renders the shirt somewhat annoying.
Swim Trunks! Bathing suits of any kind were never that common. Here is a Brittish pair, complete with inside-netting underwear stuff. It has an annoyed looking embroidered disk and abstracted line-art for the background pattern.