A righteous dude is an awesome guy who is very fun to be around, and usually associated with surfers. Everyone loves a righteous dude. He's an all-around outgoing guy.
"Woah, bro. Did you see Joe ride that wave?"
"Yeah, man. He's such a righteous dude, even surfing."
A Greek Orthodox laity who shows his righteousness to the priests and laity, basically a troublemaker who tells priests what they should do.
Righteous brother Michael: Pater you should do this, Pater you should do that, Pater you can't say this, Pater you can't say that. Oi Pater you have to do everything I tell you!
Priest: Enough of your righteousness Michael, just go away but don't smash the mugs on your way out.