It means that its good
Person 1 how is that chicken you have
Person 2 This chicken is retarded boss
Person 1 can i have some?
Very like boss. Brilliant, but in a stupid/retarded way.
*Guy falls over and takes out two people, but manages to not spill a drop of his beer.*
Person 1: Dude, did you fucking see that?!?
Person 2: Holy shit, that was retarded boss.