Another sweltering subway commute. You don’t notice the people coming and going from your train, or the ads peppering the inside of the car. You’ve conditioned yourself to block it all out. At the next stop, a gaggle of people walks in. Arms go up to hold on to a strap and, BOOM, you’re staring at an ad. In a woman’s armpit. You’re noticing advertising now, aren’t you? And it’s all courtesy of a company in Japan that’s selling ad space on the armpits of young models.