What constitutes humor on this "i before e" coffee mug text? [closed]

"i before e except after c"* is a spelling "rule" that many people remember from school or just because it's often repeated. It refers to words like "piece" to help people remember the "ie" order, and words like "conceive," where the "e" follows a "c" and is before the "i", like some similar words. But there are many exceptions to the "rule." The text on the mug lists many of these exceptions, and strings them together into a weird little story, so it's a clever and surprising refutation of the "rule." That makes the mug either funny, or for some people who have trouble with spelling, tragic.

• The full "rule" is often quoted as: "i before e, except after C, or when sounded as 'a' as in neighbor and weigh"

user8356's answer correctly describes the meaning behind the text on the mug.

As for the "humor," I would agree with Weather Vane's comment—if the mug is "funny" at all, it is not "ha-ha funny" like a knock-knock joke. Rather it is the comic irony of the mug laying out a supposed "rule" and then listing many exceptions which make the mug humorous, if "humorous" is even the right word.

The accepted answer is correct, but I want to add that I always heard the full rule stated as:

I before E, except after C, except words that sound like "A", as in neighbor and weigh

So the mug is just replacing the last part of the rhyme with an absurd list of other words that also break the rule, highlighting that even this rule is broken numerous times in English, beyond the additional words sounding like "A". The rule as stated above is meant as a rule of thumb, that is, not as a logically or fully complete rule, as that would be nearly impossible in the context of a simple rhyme.

The humor is directed at the English language itself and the many ways it breaks its own rules.