Quote Originally Posted by Alex80 View Post
"Ребята" primary meaning is "children". Form "Ребятишки" means more clearly "pre-teenagers".
Children can use "ребята" to refer to themselves.

If adults apply word "ребята" to themselves it is like they are long-term friends, from childhood, who are used to refer to themselves as "ребята". Usually it is sign of strong and long-lasting friendship.
Good point. In that sense it's NOT always a good translation of English "guys" -- which can certainly be used to address a group of strangers in a casual way (especially if they're not older than you and the group is mostly male):

"Excuse me, guys, do any of you know if there's a Chinese restaurant called Lucky Panda Garden around here?"

(Personally, I wouldn't say this to a group of men my dad's age -- I'd choose ONE of them and say, "Excuse me, sir...")