"Burning Building" joke

A brunette, a redhead and a blonde climb to the roof to escape a burning building. The firemen are on the street below, holding a blanket for them to jump into.
"Jump!" they yell to the brunette. "It's your only chance."
The brunette jumps and SWISH! They pull the blanket away, causing her to slam into the sidewalk like a tomato.
"Jump! You have to jump!" they yell to the redhead.
"No way!" she yells back. "You're going to pull the blanket away."
"No! Don't worry," they reply. "It's brunettes we can't stand. We're fine with redheads."
"OK," says the redhead and she jumps. SWISH! Again they pull the blanket away and she's flattened like a pancake on the sidewalk.
Finally, the blonde steps to the edge of the roof. "Jump! It's your only chance," the firemen yell.
"Not a chance!" screams the blonde. "You're just going to pull the blanket away."
"No, we won't! Really! Hurry, it's your only chance!" they yell back.
"Look, there's nothing you can say to convince me that you're not going to pull the blanket away," yells the blonde. "So, here's what I want you to do... put the blanket down and back away from it!"