Disclaimer: This one is more awesome than a Nintendo Sixty-FOOOOOOOOOOUR for Christmas. You will want to buy it. You will buy it.
The tshirt itself is pretty regular: black, a not too fancy “Let Your Dark Side Out” slogan across the chest. Nothing to scream for.

But then you sort of flip the shirt up onto your face and reveal its unique awesomeness in a BWAAAARRRH! BRAINS! moment.

I believe this tshirt was originally promo material for an episode of the Resident Evil video game series, but you can actually buy it from CapCom.
Reactions to this tshirt are usually mixed. Kids love it (either kids, or those who feel like they are a teenager trapped into a 35+ years old body), while random colleagues just mutter about how you’re the new weirdo around.






