One thing that’s immediately noticeable is that no one says anything is “cool” anymore. I understand that you will hear people say “that’s cool,” which would appear to contradict what I just said in the previous sentence, but you’re paying attention now and that’s good.
Coolness is a complex and elusive concept. People are commonly aware of the designations of “cool” versus “uncool,” but are not always certain how exactly to apply these distinctions. Is Justin Bieber cool? Lots of girls want to bang him; he drives flashy, expensive cars (and gets pulled over for speeding!); he vandalizes public and private property; and he’s overtly disrespectful to authority figures. He meets several qualifications for coolness, but saying Justin Bieber is cool is kind of like saying McDonald’s salads are healthy.