Three young ladies were stranded on an island: a brunette, redhead and a blonde. The brunette looked across the water towards the mainland and estimated it was roughly 20 miles to the shore. She announced: "I'm gonna try to swim ashore."

So she swam five miles but began to get really tired. At the 10 miles from shore stage, she was utterly exhausted, unable to continue and sadly drowned.

The redhead said to herself, "I wonder if she made it. I guess I should try to get to the mainland or else I'll starve to death here." So she attempts to swim ashore. Remarkably she makes it to 10 miles fairly easily, but at 15 miles the old lactic acid starts to kick in and the pain becomes so unbearable that she unfortunately drowns too...

The blonde thinks to herself, "I wonder if they made it. I think I'd better try to make it ashore too." So the blonde swims out 5 miles, reaches 10 miles, then 15 miles and finally she gets to nineteen miles from the island with the shore just in sight when she declares, "Phew, I'm too tired to go on!" So she turns around and swims back...