So what is a 'gender reveal' party?
At the 20 week scan, instead of the couples finding out their baby's sex, they ask the sonographer to keep it a secret from them. The gender is then written down and put into a sealed envelope. This is then passed to a close friend or baker who makes a large cake with either pink or blue sponge in the middle, depending on wether the baby is a boy or girl. The cake is then iced in a neutral colour and friends and family gather for a party to guess the sex of the baby, as well as this the guests have to wear colours in what they think the baby will be.
The gender of the baby is then revealed once the parents cut the cake infront of their guests!