What are these images called so we know to avoid them?

Can't speak to the images themselves, but the sites are usually referred to as "shock sites":

https://en.wikipedia.org/wiki/Shock_site

They were known as a "shock site" ( https://en.wikipedia.org/wiki/Shock_site )

The Wikipedia page for https://en.wikipedia.org/wiki/Goatse.cx is text only and without any ascii art.

I'm amused that https://simple.wikipedia.org/wiki/Goatse.cx also exists.

Oh, Goatse is that site.

I remember when I was about 15, before pop-up blockers were really a thing, someone sent me a link to that and it would keep opening popups with that image and you couldn't close all of them :-/

Sometimes people look back to the internet of the 90s with too rose-coloured glasses IMO.

For some memories... http://www.bash.org/?search=goatse&sort=0&show=25

I am personally most amused by #38659

Hey at least if you were on a 90s Mac your computer was probably unresponsive and you could skip to the inevitable force reboot. And browsers didn’t save sessions so you were in the clear as soon as you got to tabula rasa.

I’m honestly not sure you’re asking in good faith so I’m not going to add more (and if you are asking in good faith you’ve got plenty in responses to go on). Also I never knew the name of the one that’s permanently burned into my brain and I’m so glad I don’t.