Finding out the sex of your baby from the ultrasound tech has become passe. In 2012, expectanting parents are discovering whether they're having a boy or girl in a sweeter and much more public way -– with a gender reveal cake. Here's how it works: Couples ask the ultrasound tech or OB to write down their baby’s gender and they seal the note in an envelope, which parents bring to a bakery. The cake-maker then prepares a confection that reveals nothing on the outside, but is filled with either pink or blue frosting. The first slice spills the secret!