It's the scene that left a few mouths wide open – quite literally – as another season began for HBO's hit drama Girls.

The series is acclaimed for offering an honest and incisive take on the neurotic lives and sexual escapades of a group of twenty-something women living in New York; something akin to Sex & The City for a new generation.

Girls ... Marnie (Allison Williams) and her boyfriend Desi (Ebon Moss-Bachrach).

But some viewers were taken by surprise when, a few minutes into the fourth season's opening episode that aired on Monday night, they were treated to a sexual move that even Sex & The City avoided demonstrating, even though it was discussed in one episode

Marnie (Allison Williams) experienced the act in the kitchen courtesy of her boyfriend Desi (Ebon Moss-Bachrach).