slang contraction of is not, are not, am not, do not or does not.

the thing that you don’t have when you’re phones percentage is over 20

informal language;teachers hate it;used in texting,talking

<negative third person singular> Chiefly American Colloquial Contraction

A single word that is equivalent to other words such as:
1) Am not
2) Are not
3) Is not

==> Most likely originated in the Southern States of America as it flows easily with their accent but has now been used in many places around the world.

Is now in a dictionary

am not, are not, is not; have not, has not; do not, does not, did not.