Helium Balloons

Q:  Leaving helium ballons alone in a room overnight causes them to lose
    their lofty ambitions and cling to the ground.  What happened during
    the night?

A:  They became depressed.  If they had been hydrogen ballons, that wouldn't
    have happened.  When you had them filled, did you have the insides of
    the balloons coated with anti-depressants?  Sure, it costs a few cents
    more, but it's worth it.  Helium comes from the sun and maintains a
    sunny disposition as long as it's the center of attention, the life of
    the party.

    But, as soon as the party's over and all the guests have gone home, a
    grim reality hits home.  The questionable status of being the second
    lightest element sinks in like a lead balloon.  I suppose it gets to you
    after a while, perpetually being the runner-up when it comes to lifting
    power.  Always the bridesmaid, never the bride.