Former mortician here. These aren't used everywhere or all the time. If your family requests your body be embalmed, all the liquids and semi-solids of your insides will be sucked out of your guts using a hollow spear hooked up to a vacuum. If done right, there should be no liquid left in your body to leak out.
The funeral homes I worked at didn't have these. If it was necessary to plug the anus, we'd pack it with a bunch of kapok fiber. It's like cotton but doesn't absorb liquid.
Fun fact: the cork stopper in a cask, keg, or barrel is called a bung. The hole into which it is inserted is called a bunghole.
Bunghole is also a euphemism for anus. So, a question for any morticians here: can we start calling the corpse plug a bung? I’d consider a career change if I got to tell people about the bung in grandpa’s bunghole.
All conservatives are going to start choosing cremation. My parents were cremated and that brings comfort to my heart. Ass for I, I will require a big plug please. Then you can cremate me. It's just in case I'm still alive at the time. You never know, I could be given one final parting gift that I would gladly accept. LOL. C'mon conservatives! The water is fine!
I've been following him since the LiveJournal days. Back when he made things like Emo Assault Squadron (available on YouTube). He still does hearse work but hasn't put out anything big in some time.