Three blondes stranded on an island

There are three blondes stranded on an island.

Suddenly a fairy appears and offers to grant each one of them one wish.

The first blonde asks to be intelligent.

Instantly, she is turned into brown haired woman and she swims off the island.

The next one asks to be even more intelligent than the previous one.

So, instantly she is turned into a black haired woman.

The black haired woman builds a boat and sails off the island.

The third blonde asks to become even more intelligent than the previous two.

The fairy turns her into a man, and he walks across the bridge.