Here are a couple that I heard of a while back...
"Two blondes were in a parking lot trying to unlock the door of their Mercedes with a coat hanger. They tried and tried to get the door open, but they couldn't. The blond with the coat hanger stopped for a moment to catch her breath, and her friend said anxiously, "Hurry up! It's starting to rain and the top is down."
"A blonde calls her boyfriend and says, "Please come over here and help me. I have a killer jigsaw puzzle, and I can't figure out how to get it started."
He asks, "What is it supposed to be when it's finished?"
The blonde says, "According to the picture on the box, it's a tiger."
Her boyfriend decides to go over and help with the puzzle. She lets him in and shows him where she has the puzzle spread all over the table.
He studies the pieces for a moment, then looks at the box, then turns to her and says, "First of all, no matter what we do, we're not going to be able to assemble these pieces into anything resembling a tiger."
He takes her hand and says, "Second, I want you to relax. Let's have a nice cup of tea, and then....." he sighed, "we'll put all these Frosted Flakes back in the box."
"There is a brunette and a blonde hanging over the edge of a cliff off a piece of rope. They realize that the rope will break if one of them doesn't let go and they will both fall to their deaths. The brunette starts this big heartwarming speech about how she is going to sacrifice herself. At the end of the speech the blonde starts clapping."
Didn't know that blondes made things... here are a couple I also heard of...
"Screen door on a submarine"
"Helicopter ejection seat"
"Battery-powered battery charger"