Heard this one in 1959, didn't get it for a decade.

Pretty blond woman seeking to hold onto her youth, spots an add for 'milk bath treatments for healthy skin'.
So she enters the business and inquires as to how much it would cost for a tub, and the proprietor asks "Whole, or Pasteurized"?

She says, nah, up to my tits will do just fine.

OK, I'm going...