A young couple sit closely together in a hospital room, peering anxiously at the ultrasound screen and waiting for the scan to reveal the identity of their precious new love.

The nurse indulgently asks, "Is it your first?" and the couple nod eagerly. But what appears on the screen is not a boy or a girl - it's a burger.

Burger King France has launched a Mystery Burger promotion with agency Buzzman, selling unbranded white boxes labeled only with a question mark. For two euros ($2.4) and until Sept. 25, customers can try their luck and take home one of ten different burgers picked at random. (A regular Whopper costs four euros.) The idea is to encourage people to rediscover the full range of Burger King products.

In the ultrasound room, the nurse declares the contents to be a Classic Whopper, before changing her mind. "It's a Steakhouse," she says, "Do you see the bacon jutting out?" The couple are elated, until she changes her mind and says that it's not bacon, it's cheese.

The ad finishes with the line, "The only way to find out which burger is in your Mystery Burger is to open it." Buzzman's film will be seen on TV and online, and backed up with out of home advertising.