T-Shirt of Indeterminacy

Heisenberg was pretty certain about one thing: uncertainty. Incredibly simplified for comprehension by our merchant monkeys, Heisenberg figured out that as you measure a moving particle's position or momentum, you affect the other. In fact, the more accurately you measure one, the more you throw the other off. Now, in normal everyday activities, this doesn't really figure in. But on the quantum scale of the atom, these things are HUGE.

We're pretty sure this shirt is currently in the warehouse, so we can't be certain about how quickly it's wending its way to your closet. Or, if you'd prefer, we can get you information on how quickly the shirt's moving toward your mailbox, but then we can't tell you where it is. Okay, well, that's not entirely true, because our t-shirts don't currently come in sub-atomic sizes. We can, however, tell you the probability that the electrons that make up this shirt are heading your way is far higher if you've actually ordered it than if you haven't.

Black, 100% cotton t-shirt reads, "I'm Uncertain About Quantum Mechanics."