it basically means "stop lying", "I don't care" and "fuck off/
fuck you" depending on the phrase it's used at.
first
time used by two students (Z.Yacine and Y.Abdelfettah - around
2020) when they were looking for a way to insult their professor without him being aware of it, later on it became their way of insulting everyone, then the word caught others' attention and a variety of other students started using it.
origin of the word is ترخف
person 1 : believe me
bro, I tried did my best but did not work
person 2 : chisme.
or
professor : you have to solve all these eauqtions by
tomorrow, if not you get an
F.
student ; Sir, chisme.