Here's a humorous one for you:

“The children now love luxury; they have bad manners, contempt for authority; they show disrespect for elders and love chatter in place of exercise. Children are now tyrants, not the servants of their households. They no longer rise when elders enter the room. They contradict their parents, chatter before company, gobble up dainties at the table, cross their legs, and tyrannize their teachers.”

- Socrates

...even Socrates eventually became an old curmudgeon complaining about /kids these days/.

Needs more quotes.