Three blondes were walking through the desert when found a magic genie's lamp t he said,

Three blondes were walking through the desert when found a magic genie's lamp
t he said, "I will grant three wishes, one for each of you." The first said,
"I wish I were smarter". So she became a redhead. The second blonde said "I
wish I were smarter than her." She became a brunette. The third blond said
"I wish I were smarter than both of them." So she became a man.