For an amusing but harmless example, see the Amelia Bedelia article. It's been long since reverted, but I'm sure there are many similar prank edits that survive to this day

https://en.wikipedia.org/wiki/Talk:Amelia_Bedelia

https://www.dailydot.com/unclick/amelia-bedelia-wikipedia-ho...

(EDIT: please use noscript if you visit the daily dot link, it's a terrible 3rd party spam site)