Fountain (The Urinal) by Marcel Duchamp. He didn't make the urinal. He found it, decided it was good enough, and got it into an exhibit. There you go.

Erased de Kooning is a much more obvious example. The artist erased a drawing from another artist, resulting in a mostly blank piece of white paper.

https://en.m.wikipedia.org/wiki/Erased_de_Kooning_Drawing

I think there is an important difference between art that people will go to see in a gallery, museum, or in public, and art that is bought at auction. I have no interest in seeing AI generated paintings either at home or in a gallery, but I would go to an art museum specifically to see Fountain by Duchamp. Fountain encourages people to appreciate the world around them by taking an everyday readymade and probably overlooked object and placing it in a gallery where they can see it more fully.

What's fun about Fountain is the the original has been lost, so you can only see a, "recreation" of it. Since it was initially just a found object of a mass-produced item, this wasn't a problem - but still, Duchamp could sanction "official" replicas.

Ah, love it.

Also fountains usually have some sort of water works going on. Could be that Duchamp was asking people to piss on the Readymade! I'm sure a few have.