Marooned

Three dumb blondes were shipwrecked on an island. They came across a magic lamp and a genie came out.

The genie said that he would grant them each a wish. The first blonde asked to be made smart, the genie turned her into a brunette and she swam off the island.

The second blonde asked to be even more smarter, so the genie turned her red hair and she built a boat and sailed off the island.

The third blonde asked to be made the smartest, so the genie turned her into a man and he walked onto the bridge, and off the island.