Christine Quinn has turned Pamela Anderson down. As Page Six reported, the busty former “Baywatch” babe asked the City Council Speaker to be her date for a gala next week promoting a ban on horse-drawn carriages in New York. Anderson even playfully added Quinn could bring her wife because, “Three’s company!” But Quinn replied in a staid letter, “Unfortunately, due to prior commitments, I won’t be able to join you.” The mayoral hopeful added, “I know you care very deeply about the safety and well-being of these horses . . . the NYC Council and I do, too.” Even a performance by Joan Jett couldn’t entice Quinn to change her plans.