WORDS. the interrobang

i'm not entirely sure how or why i came across this, but i recently found this strange little grammar anomaly. its a punctuation mark that is meant to be an exclamation point and a question mark. strange. in the official rules of grammar it is not allowed to have more than one exclamation point at the end of a sentence. so when ever anyone ends a sentence like this: 'he said what?!?' it is improper grammar. instead, you are supposed to use the interrobang. huh. will the wonders of the english language ever cease?!?