Does it sound unnatural to you (natives) when people skip 's' ending of the verb in 3rd person? Heard it many times (e.g. in 50 cent songs - she go, she have, etc.) and always wondered how much it sounds ok.
That's a common detail in the variety of English where they do that, e.g. one that 50 Cent and many rappers use, namely AAVE.
In AAVE, in particular, in the present tense you don't inflect for number or person (which is a long fancy way of saying that the one item you do inflect in standard English, present 3rd person singular, you don't in AAVE)
It is not common for a newscaster to speak that way, but is perfectly natural sounding informally (if you're speaking AAVE). But if you just drop that one thing into your speech (making sure you're following the rules the right way) it'll still sound weird if you don't have the accent and the other aspects.
If you are a language learner, you will want to avoid this, because presumably you will want to simplify your learning of English and only learn one variety, most likely the standard general American variety. But if you find that you are speaking with others frequently who speak this variety AAVE or nearby AAVE, then try to learn all their slightly different rules.
This is a grammatical characteristic of African American Vernacular English (AAVE):
Present-tense verbs are uninflected for number/person: there is no -s ending in the present-tense third-person singular. Example: She write poetry ("She writes poetry"). Similarly, was is used for what in standard English are contexts for both was and were.
I'd ground my kids for talking that way. No, it's not proper English. Yes, it is a part of hip-hop society and so is wearing your pants half down the crack of your butt. It's a rebellious sounding way to talk. Please don't talk like that in a job interview or anytime you want to impress someone.
From the King James Bible: "And if thy hand offend thee, cut it off: [...]". It would have been similarly possible to say "Cast he the first stone who is without sin." though not even the KJV version does it like that.
Bible aside, there are subjunctive mode uses of the third person which are correct (though a bit quaint these days) without "s" (or without the Early Modern English equivalent "th").
That is, however, not the usual grammatical construct employed by rappers.