Just after Pearl Harbor, as the US was entering WW II, they started amassing troops in England. The locals, being grateful for America's involvement, decided they needed to show their appreciation. But lacking in most necessities, they were at a loss for a way.

The local prostitutes decided it was their turn to help Queen and Country. They were appalled with how many of the incoming servicemen were virgins.

They decided they would give each one of them a personal "Thank you!" The other locals, knowing of this, started holding these prostitutes in high regard, and greet them happily, instead of looking down on them .

So it came, the origin of the phrase, "Thank you for your cervix."