you ain't shit
= You're nothing.
However, 'you ain't shit' isn't necessarily an insult. You can comfort someone by saying that they are not shit.
You ain't shit vs. You are shit is definitely not the same. 'Ain't' is a general negation vernacular term.
Synonyms for You ain't shit
On this page, you will find 30 slang terms related to you ain't shit. Some of the top words include: aintcha, toof, Inchromulent, aight, meh?, and 25 more.