The expression buttox appears to have various meanings depending on who uses it. One thing is for sure, though; it definitely has something to do with butts.
One definition states that it is simply a more fun way to spell “buttocks”, the not-so-offensive term for a persons behind.
Another person states that it is a combination of “buttocks” and “botox”, describing a person who has enhanced their butt’s shape and size with botox and other fillers.
The last definition, a bit far-fetched, describes that “buttox” is when someone gets botox injected into their forehead, but the job is done wrong, and because of a cleft in the middle it looks like you have a butt on your forehead.
The origin of the term appears to be just as ambiguous as the meaning. It seems to have appeared around 2010, and the only information that can be found about the term are its various definitions.
Apart from the ambiguous definitions of the term, it seems to be a common misspelling of the English term “buttocks”, and numerous spell-checking web pages have instances explaining which one is correct.
Nevertheless, the term sounds the exactly like “buttocks” when said out loud, therefore the slang is mainly used online.