Some moms and dads have the ultrasound technician write the child's sex on a slip of paper that is placed in an envelope. It's then dropped off at a bakery where a cake is baked in the appropriate color and iced to hide the news. When the parents-to-be cut into the sweet treat, they learn about their future offspring. The idea gained national attention when Josh and Anna Duggar cut into a pink cake on the Today Show to learn that they were having a girl. The concept is gaining momentum as more couples opt to hold soirees to celebrate their impending offspring.
Source: Grey Grey Designs