There was an old spelling rule: "i before e, except after c". Unfortunately, there are so many exceptions to the rule that this old rule is useless. Some exceptions include: feisty, heist, weird, beige, foreign and neighbor. :D These all have ei in their spellings.

It's a way of remembering using something called "assonance" in the English language, the spelling of words that typically consist of the letters "i" and "e". There is often some confusion on the correct sequence of the i and e in words such as "convenient", the rule says to generally use the letter i before e except in the above-mentioned cases such as "feisty", "heist", "weird", "beige", "foreign" and "neighbour".

It's a joke, emphasizing the unreliability of a spelling rule. It is hard for native English speakers to remember the spelling of words like "receive" and "believe." There is an old rule which, oddly enough, is actually helpful because it works in exactly the cases that are hardest to remember. The rule is "I before E, except after C." However, it has a ludicrous number of exception. As a matter of fact, the rule as I learned it in school is: "I before E, Except after C, Or when sounded like A, As in 'neighbor' and 'weigh,' Except: weird, leisure, neither, Seize, inveigle, either." But that rule in itself fails to cover literally dozens of exceptions. In addition to those mentioned in the joke, there are also: ancient, conscience, caffeine, concierge, counterfeit, deity, financier, heifer, heirloom, protein, reimburse, seismic, sleight, species. Weirdly, though, most of these are not hard for native English speakers to remember.