oh. my. god. pic.twitter.com/DpXu7bpqkA
— Stelian Firez (@stelian) April 15, 2016
A few months ago, in response to a horrible web form for entering phone numbers shared by Stelian Firez, Twitter responded with a barrage of deliberately horrible and obtuse design alternatives, seemingly in search of the worst option possible. Many of these are collected and archived here.
Then more recently, Reddit set to the task of designing the worst possible volume sliders.
Hilarity aside, there are certainly lessons to be learned in trying to design a worst possible UI, as well as in studying these fine examples.