One cat got himself an abscess on the tip of his head from his chirping at the wrong cat on the back wall and getting a slap for his trouble. Noticed that he felt a bit spongy and moved the tiny clump of stuck together fur to look at his skin - to be met by the most disgusting stench and green/yellow stuff pouring out as I'd taken the plug out.
Whilst DP was on the phone waiting for the next available vet appointment, I decided the only way to deal with it was to clean it with cooled boiled saline and coax the gunk out every three hours so it didn't close up again.
By the time the vet saw him the following day, they said I was doing a brilliant job - he just needed some cheap antibiotics and regular cleaning.
By the time it stopped producing filth about ten days later, I was having to stroke from his throat, his face under his eyes and his chin to bring it up to the tiny hole I reopened each time at the top of his head. I'd then gently lift the surrounding skin and flush it out with more saline. And he purred throughout - for weeks afterwards, he'd jump onto my lap to have the same areas fussed, but only started purring if I gently tugged the regrown fur at the top of his head.
Another cat got an egg sized fluid filled cyst on the top of her head that the same vet said wasn't worth the risk of anaesthetic to remove, but I could drain it whenever it was full. Once a fortnight, a sterile needle, and a jet of Amber liquid shooting out onto kitchen roll.
The same cat had a partial thyroidectomy. A year later, she was pushing her throat into my hand for fuss and I caught something in the corner of my index fingernail. As I took a firmer grip on it, she slowly pulled away for me to have a six inch long piece of blue suture material in my hand.
Animal sport is great.