Traditionally this term "Greying of America" talks about how the population of America has more older Americans (aka Adults, etc.) Another way this is said is that the "standard" or "median" age of America is growing. In general, no matter how this is referenced to/about, when you state this you are stating that the population of America (and/or America itself) is becoming older.
I am not sure what you asking, but since Justin doesn't want to go to the graduation party because he know he going to be embarrass from not gradating with the rest of his friends.
