I don't know who j4rno is, but if he was Italian I'd assume he rejected it as paisan is the short form of paisano (which is actually spelled "paesano" in proper Italian) and, while I am well aware that it means "bro/fella" in American english, in Italian it means "peasant".
As per our version of "Bro", some use the word "Fratè" which comes from fratello, which means "brother" (would you have guessed?) but that's considered kinda lame. Most people just borrow the word "bro" directly from English.
A cool way to call your mates in northern Italian would be "vecio" which literally means "old" but is used only among young people to call each other and it equals to "bro".
Yes I know that calling each other "old" if you're young doesn't make any sense. We are weird people