Gravity can be annoying.  Gravity does not take vacations.  It is relentless.  Most adults courageously fight the good fight against gravity every day.  Teenagers, on the other hand, have not yet taken up the struggle. Perhaps teenagers intuitively sense something that some theoretical physicists are now considering: could gravity be just a grand illusion???  Uplook Magazine December 2006, p.4.  References:  J. Maldacena,  "The Illusion of Gravity," Scientific American, November 2005, 56-63.