Oh, this one was played on me over 20 years ago - in a college class - by the tutor!
I was the only girlie, so used to have to put up with a lot of ribbing and practical jokes (today it would be grounds for a sexual harassment claim, but things were a lot different back in the 80s - we just had to put up with it).
Anyway, I can’t rememember the exact details, but do remember it being a very long and convoluted story, before it got to the “dog-bite” bit. And I remember being very reluctant to touch the tutor’s neck in the first place - as if that wasn’t yucky enough, before it even got to the grand finale.
Should have stood my ground, and said: “No thanks, I don’t want to touch your neck - I’ll just take your word for it.”
No, never even occurred to me! Maybe it’s just not my kind of humour, but the circumstances in which it was played probably didn’t help. By a tutor, in front of the whole class, didn’t exactly leave me thinking: “Great joke, must try it on somebody else”. I reckon if he’d tried it on one of the chaps, he might have got punched - which is probably why he didn’t.
I’m sure your example was nothing like that; context is everything.