Not quite with a GP, but a sonographer. When my boy was in the womb, we went for a scan. The guy asked us if we wanted to know what sex the baby was going to be, so we said we did. He said he was a boy and, as he no doubt said to everyone else, "he won't be afraid to be naked in the showers". I was looking at him measuring something on the screen and asked the bloke "that seems quite big, are they usually that well developed?" to which his reply was that he was measuring his femur!!