South Park: The Stick of Truth - Irritable Bowels Achievement

**This is a Missable Achievement **

First, you need to unlock Mana, which you get after Cartman teaches you your first fart spell in Kupa Keep. Then you need to acquire some Mana potions. You can use the potions outside of battle to actually fill your meter. Then go into battle and you'll see your Mana meter flashing with a warning sign. This means one more mana potion will make you shit your pants. Eat the mana potion to shit your pants.

Alternatively, while fighting Jimmy, at some point he will likely use an attack called Brown Bomber. He will play the brown noise, and if you don't block, it will cause your mana meter to max out and you'll shit your pants, unlocking the achievement immediately.