Just when I thought maybe there was an original question on AskReddit… then I googled it.

https://amp.reddit.com/r/AskReddit/comments/25a1i8/what_would_chairs_look_like_if_our_knees_bent_the/

https://amp.reddit.com/r/AskReddit/comments/31k873/what_would_chairs_look_like_if_your_knees_bent/

https://amp.reddit.com/r/AskReddit/comments/1kwujv/if_our_knees_bent_the_other_way_what_would_chairs/

https://amp.reddit.com/r/NoStupidQuestions/comments/5e0j8i/if_our_knees_were_backwards_what_would_sofas_look/

https://amp.reddit.com/r/Showerthoughts/comments/6bgipf/what_would_chairs_look_like_if_your_knees_bent/

They even have the exact same comments.