a. That girl is retarded for stealing when she is rich as hell!
b. Damn boy, your website is looking retarded!
c. Man, it's boring in here. Let's get retarded!
The word retarded in slang means to get stupid; just act how you want to; dance like you don't knowwhat you're doing. One normally becomes "retarded" after popping an ecstasy pill or doing some sort of drug.
Remember though....ThIzZ iZ wHaT iT iZ