Sketch Reward #7 - What's the potty for again? (Patreon)

Fresh from my stream just now! I was gonna go sleep, but I realised how much I have left to post this month, and how I hadn't done so today yet, so.... :-D 

Obviously, done for Sierra. Obvious, not cause I drew her so well, but who else would forget what a toilet is meant to be used for? ^_^