A fantasy world

A world full of magic and monsters. Swords and heroes! An interesting place to live, especially this one. For you see, magic and skills use mana, and in this world that mana is stored in the bladder and bowels of the user. Or, to put it more accurately, the "waste" mana is stored in the bladder and bowels.

Whenever someone uses magic or a skill, the caster's mana gets used up in the spell or skill and converts into urine and/or feces, depending on what was used. This then gets stored where else but the nether region, forcing the user to either search for a latrine, next to impossible, or lose all control where they stand.

Fortunately, this world has invented diapers, and not just cloth, but actual disposable diapers, similar to the ones you know but made from a plastic-like substance. Wearing a diaper in this place is so common that their society is based around it.

If this is the place you want to go, then just think of who you want to be and you'll be instantly teleported there.