“Elves do not need to shit. There are no execratory processes happening within the elven body. There are no toilets in Lothlorien. Celeborn tells Gimli to just “go on a tree, like a hound”. Legolas spends the entire quest feeling sad, left out and excluded from the camaraderie building activity of the communal morning shite. Half-elves may need a shit but only sometimes. Like when they’re particularly sad, or ate something bad. When Finrod discovered humans he was fascinated by the concept. Lúthien (re-released edition) and Arwen had the capability to take a shit but chose not to. Elros wanted to but couldn’t. With the Maiar it’s Russian Roulette. Saruman can’t but tells everyone he can. Mithrandir can. Sauron won’t, which explains a lot.”
— JRR Tolkien, Laws and Customs Among the Eldar