12. Armpit cooler
Believe it or not, this thing exists, and you can buy it in Japan. Japan has very humid and hot summer season, and sweat stains are hard to avoid. Luckily there is an invention which can keep your armpits cool(er). Thanko Electric Armpit clip-on cooler is a small, battery-run device which you can attach with a clip on your sleeves. Batteries can hold for around 5-9 hours, and the cool air from the device will make the hot summer bearable.
