It s a word that we use only with male persons .In some areas(in the countryside) is used between friends. Ex : Ba Ioane, da-mi si mie te rog 10 euro ... (Hey you,John ,please give me 10 euros) If you use it with someone who you ve just met or someone who is not a close friend,it can be even an insult.

Thanks, sorry! :) didnt knew it!

It is not polite to use this word.It is a jargon.For example,some peoples use it when they need atention from another person but in a bad way..." hey you" , "yo man". So,is better to don't use it ..