Shao-waah
It's just the word shower translated into ninja. They usually use wah-tah to take their shao-waahs!
Boy: Hey ninja!
Ninja: Waa!
Boy: Do you take showers?
Ninja: If you mean shoa-waahs! Then yes! I take shao-waahs, and I like to use wah-tah!
Ninja: Waa!
Boy: Do you take showers?
Ninja: If you mean shoa-waahs! Then yes! I take shao-waahs, and I like to use wah-tah!