Oh my, a Brunette, a Redhead and a Blonde...

A Brunette, a Redhead and a Blonde escape a burning building by climbing
to the roof.  Firemen are on the street below, holding  a blanket for them
to jump in.  The firemen yell to the Brunette,  "Jump!  Jump!  It's your
only chance to survive!"  The Brunette  jumps and SWISH!  The firemen yank
the blanket away.  The Brunette slams into the sidewalk like a tomato. 

"C'mon!  Jump!  You gotta jump!" say the firemen to the Redhead.

"Oh no!  You're gonna pull the blanket away!" says the Redhead.

"No!  It's Brunettes we can't stand!  We're OK with Redheads!"

"OK," says the Redhead, and she jumps.  SWISH!  The firemen yank  the
blanket away, and the lady is flattened on the pavement like  a pancake.
Finally, the Blonde steps to the edge of the roof.  Again, the firemen
yell, "Jump!  You have to jump!"

"No way!  You're just gonna pull the blanket away!" yelled the  Blonde.

"No!  Really!  You have to jump!  We won't pull the blanket away!"

"Look," the Blonde says.  "Nothing you say is gonna convince me that
you're not gonna pull the blanket away!  So what I want you  to do is put
the blanket down, and back away from it..."