Sorry, this design isn't "deliciously dark" or "wickedly fun." It's sick and wrong. None for me.
The design also falls short of shirtWoot's usual selections. It's not clever, beautiful, or even funny. Part of the problem is that the dangers shown seem realistic. Sorry, but if I saw this shirt on someone and tried to interpret its meaning, I'm not going to have enough time to think, "Wait, there's no way you could push a pin through Smarties--they're too hard! Ha-ha, this shirt must be really funny!" As others have pointed out, even the glow-in-the-dark aspect could have been handled better--it doesn't reveal anything previously unseen, or change the shirt's meaning.
One-shot visual humor lies in the unexpected juxtaposition of what is perceived versus what is revealed. If the candy being X-rayed revealed that yes, there was stuff hidden inside, but it was harmless stuff that kids hate (cherry tomatoes in a box of malted milk balls, Brussels sprouts mixed in a package of jawbreakers, a rolled-up math quiz inside a Tootsie Roll wrapper, prune juice inside a honey-stick, etc.), that could have been funny.
For those wooters waxing sentimental over this shirt as a reminder of having to stand in line to get your candy X-rayed to protect you against a horrible injury, what the heck are you thinking? Going to get the candy X-rayed was never the fun part--you were supposed to be making memories about the good parts. Are your fond memories of Christmas all about the cardboard that your toys came in?