From The Art and Popular Culture Encyclopedia
There is a category of blonde jokes that employ the dumb blonde stereotype for their effect. Blonde jokes have been criticized as sexist by several authors, as most blondes in these jokes are female, although male variations also exist. Research indicates that because of this, men find blonde jokes significantly more amusing than women say they do.
Many blonde jokes are variations on other stereotypical jokes. Blonde jokes nearly always take the format of the blond(e) placing himself or herself in an unusual situation, performing a silly act because he or she misconstrued the meaning of how an activity is supposed to play out, or making a comment that serves to highlight his or her supposed promiscuity, lack of intelligence, or cluelessness.