I have news, "ain't" IS an officially recognized word, no longer considered slang, a conjunction of is not with the same meaning of isn't. It's in the dictionary, it's proper grammar.

snip:
[link to www.merriam-webster.com]


ain't
\ˈānt\
Definition of AIN'T
1
: am not : are not : is not
2
: have not : has not
3
: do not : does not : did not —used in some varieties of Black English
Usage Discussion of AIN'T
Although widely disapproved as nonstandard and more common in the habitual speech of the less educated, ain't in senses 1 and 2 is flourishing in American English. It is used in both speech and writing to catch attention and to gain emphasis