How should a Rick Roll link (obviously hidden from sighted users) be marked up for assistive technology? That's the question Eric is answering, and the result can be summed up as: preserve the whimsy! It's great seeing an approach to WCAG interpretation that both considers the full intent of that spec and attempts to preserve experience as much as possible. That's always felt like the right method to me, so nice to see that validated 😁
The interesting part here is whether you should announce the fact that you're linking to autoplaying media (if, in fact, that is the case). I fully understand the argument, but can see justification that this also slightly contradicts the core message. I guess the best solution in this instance is to have a link that seems to be going to one video (and therefore can be visually and audibly tagged as linking to media) but which lands on a Rick Roll, though that might still take some of the fun away (though, as I say, I do understand that "fun" will not be had by people whose day is actively made worse/unbearable by sudden noise or movement, so yeah... pranks are a little hard for inclusion 😬).
(Also, the provided example of a "surprise" link is exceptional, but I leave it up to you to discover it by yourself.)
On the actual wording of WCAG 2.4.4 specifying that links provide an equal experience:
I love this. This is all about maintaining an equivalent experience by not over-describing something for only a certain subset of people. Here, the goal is to preserve the author’s intentional act of creating a sense of curiosity, regardless of the way someone interacts with technology.
2.4.4 is as much about preserving the intent behind why the link was important enough to be added as it is that the link’s accessible name makes sense. If the author intended to be purposely ambiguous, we need to honor that and not ruin the joke.
On Eric's suggested solution:
“Visit for a surprise” preserves the author’s intent. It’s a little mystery object you can poke if you’re feeling adventurous. If you’re not, you can carry on with whatever you were visiting the site for.