"Patience you must have. Fiber to your diet you must add."
Or imagine him back on Coruscant in the Jedi temple, waddling off to one of the restrooms and hopping up on a space toilet. Imagine one of the Jedi doesn't know he's in there and accidentally opens the stall. Yoda scowls, covers up his junk, and demands he close the door.
Now imagine E.T. doing the same, back on his ship. It kind of ruins the character, right? Don't say they don't excrete waste, either -- we see both of them eat and drink; it has to go somewhere. But as characters they're so wise, innocent, and otherworldly that it feels like an insult to imagine them doing something that literally everyone does. That's bullshit. A real creature, that we're supposed to accept exists in that universe, shouldn't blow a hole in our imagination with a simple bowel movement.
Now, imagine Elsa from Frozen, in her Ice Palace.
Hold it innnnnnnnnnnn, hold it innnnnnnnnnnn!
Does she have to go off and piss in the snow outside? Does she have a huge yellow dome of frozen piss somewhere she just keeps adding to? Or is she so pristine and perfect in the sparkling evening gown she wears around the house that you can't picture any piss scenario? Apply the same logic to the Elves in Lord Of The Rings -- is it hard to imagine Legolas taking a shit in the woods and then burying it after wiping his ass with some leaves or a passing rodent?