I ain't on that shit! - You're telling someone you're not going to be part of their

You're telling someone you're not going to be part of their stupid mess or their stupid problems.

I ain't on that shit! You're making a mess and I ain't going to be part of it.

I ain't on that shit! You're getting in trouble and I ain't going to be part of your trouble.

I ain't on that shit! You're acting like a fool and I ain't going to be part of your foolery.