My pal Christy at Instructables says:
Our intern Bilal (a runner-up in the last laser cutter contest) painted and laser-engraved his fingernails, then realized he could use press-on nails for a safer and more portable version. Of course, since concept is everything, he went for an epic Beards vs. Mustaches historical character smackdown. (At any rate, it's much less gross than the laser tattooing.)
Laser-engraved fingernails (Instructables)