What is the issue with the HTML Standard?

Section 13.2.6.4.7 (‘The "in body" insertion mode’) says:

An end tag whose tag name is "sarcasm"

Take a deep breath, then act as described in the "any other end tag" entry below.

Is that serious? whatwg/fetch#147 (comment) pointed me to this; at least in that context, the answer is clearly ‘no’.

Shortly after that, this specification continues:

An end tag whose tag name is one of: "a", "b", "big", "code", "em", "font", "i", "nobr", "s", "small", "strike", "strong", "tt", "u"

Run the adoption agency algorithm for the token.

Is that serious? Initially, having just seen that </sarcasm> joke above, and being unfamiliar with the adoption agency algorithm, I believed that the answer was also ‘no’. But after further reading of the specification, it became clear that the correct answer was ‘yes’.

The </sarcasm> joke is an unnecessary and confusing addition to an already long and complex specification.

While trying to check if this issue had already been reported, I found #5382. In that issue, it looks like the original suggestion is serious, but the first reply is a joke. That reaffirms that the </sarcasm> joke is creating unnecessary confusion.

The </sarcasm> joke and any similarly confusing jokes should be removed. Humor can still be used effectively in examples, like the one that applies text transformations based on [XKCD1288].