Again folks, we must remember that there is absolutely no Slavic influence on grammar, pronunciation or anything else. Or if there is some influence it is “minor” and “very little” :P
Nonetheless, time to examine the (ordinary) word ba (bah), which while short and sweet, is important.
The DEX has a perfect definition:
(Expressed in opposition to an earlier (stated) negative idea or question, used especially as a rejoinder)
In other words, if someone you’re talking to says something and you wish to contradict them, you often say “ba” as the first word in your sentence.
The easiest way to think of ba is the phrase “on the contrary” in English.
Example:
Romanian: Dar esti american, omule.
Random Person: Ba nu, sunt roman!
Therefore the rejoinder here is “On the contrary, I am Romanian!”
There are several idiomatic expression in Romanian which use ba but what’s described above is the standard way to use this word. Occasionally ba is used simply by itself to indicate the disagreement.
Romanian: Dar esti american, omule.
Random Person: Ba, sunt roman!
AND NOW YOU KNOW!
All Things Romania 
Folks, keep in mind the word is ba and not bă. :)
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Yes, ba is the masculin for grabbing a male’s attention and if you want to grab the attention of a female, instead of “Ba, Ioan” one says, “tu, Simona.”
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Ya, it can be used instead of “you” like in “Ba prostule” – “You fool” or instead of “Hey” like in “Ba, esti un prost” – “Hey, you are a fool”.
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there is another use for the word “ba” spelled as bă. It`s not used as a negation but as an interjection for masculin gender. something like: “bă, frate!” meaning like “you, bro!”. i hope i made myself clear! :D
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