Your intent is good, but both of those statements are still somewhat offensive. If the guy is a stranger just refer to him as you would any other guy, no need to add race into the equation. It's not so much about being politically correct, it's your attitude. Once you know black people you can call them whatever the fuck you want if you're joking and they know you don't mean it. That's the way it is with all races...I should say ethnicities seeing as there's only one race. Just a matter of respect and familiarity.