In case you've ever wanted to transform your mug into an Aperture Science Portable Quantum Tunneling Device, crafter Two Horns United has built one that fits right on your chin. I imagine it's incredibly useful if you're the kind of clumsy individual who frequently finds yourself plummeting off cliffs face-first. Wear it to the Portal golf course for extra thematic resonance.

[Two Horns United via Fashionably Geek]