Possible Clues:

• If young, you can't beat this papaya gel -- I'm itching to sample
• Birthdate-based restriction
• 17, for an R-rated movie
• Disqualification of a particular demographic from doing something
• 18, for Youth Olympic Games athletes
• Discount ticket restriction
• Regulation regarding length of time one has lived
• Generation against ceiling for the over sixty-fives
• Restriction based on years
• Turns up, Timothy at one stage had a ceiling that was restrictive to the youngsters, for example