Holy. Mother. Of. God.

Back story: last Monday I went to the vet with ze boyz to have them vaccined and examined. (They're in prime shape, BTW) After the vaccination I was happily surprised to see that Cornelius didn't develop any bumps -- this happens sometimes when there's a reaction to either the serum or the carrier substance. No bumps for the whole week. On Saturday, mega-bump on Cornelius's neck. Unfortunately I hadn't paid close attention to where the doctor had actually injected the serum and thus wasn't sure whether this could be a simple vaccine bump or something else.
Bump didn't diminish, so I decided to go back to vet today and let him have a look.
Cornelius was put into carrier bag.
He's normally the most laid-back of cats, but he does NOT like being put into the bag.
The bag's flap is closed by means of a zipper, but -- like suitcases -- it's a zipper with two pieces which meet in the centre. Putting a paw into the small remaining hole is easy, and escaping would therefore be kitten's play. So I threaded a piece of cord through both holes and made a knot.
Cornelius, completely beside himself, managed to squash his head through the tiny, tiny opening and would have strangulated himself, had I not ripped the whole thing apart in time. His tongue was hanging out, and he was barely able to breathe.
Vet visit was cancelled. I merely phoned, and he confirmed that he'd injected one of the three shots into the neck.

Silly me, I could've saved myself the trouble.
Still, I'm glad it happened today and not on Friday, when I've got to catch a flight. Now I'm forewarned. But holy shit, what a fright...