The diet water is japanese, and in japanese they use the word "diet" to mean any form of losing weight (including exercising and stuff).. They probably put "diet" on that water to express the notion that if you drink water, it will help you lose weight..
[–] NassTee 0 points 3 points 3 points (+3|-0) ago
The last one is for people with OCD who need to poop once then wash their hands five times.