Some people use a pen or pencil to write ads. Others use an electron microscope. To emphasize the precision of its blades, Gillette and French ad agency CLM BBDO, with help from scientists at the University of Nottingham who are not currently curing cancer, used nanotechnology to etch the world’s smallest ads on the whiskers of a man’s shaven beard. Each ad is less than 100 microns in size.
Obviously, that makes them impossible to see, so Gillette blew the images up for print and poster ads. There’s also the video below, outlining the process. Obviously, Guinness has been brought in to verify the world record. Somewhat off-puttingly, some of the ad-hairs were left in men’s bathrooms at airports (hopefully in plastic bags or something), along with QR codes you could scan to learn more about the ads written on them.