The fear one generation of adults holds towards the younger generations succeeding them. Often times coincides with the inability to recall one's own childhood and use this as perspective when formulating opinions about "today's" youth.
The feeling that entertainment, social practices, fashion, etc was superior in one's past when compared with how these are practiced by younger generations in modern times.
Jim: "Back in my day, we weren't allowed to have any fun, and didn't want to either! We plowed fields and went straight from toddler to adulthood... it was great!"
Bob: "Jim, I'm afraid you're suffering from what's commonly known as juvenoia."