My own impression of the behaviour is that New Wife's job is something they consider "naughty," and they are having a grand time thinking "OOOH, wouldn't the grownups be shocked if they knew what she REALLY does! Teehee!"
A pretty juvenile approach, and the best response, as with most juvenile humour, is to ignore it. In fact, the more juvenile they behave, the less likely it is that the job is anything particularly shocking to anyone who's actually an adult about things.