The way I told them I went to a balloon store told them to inflate a black balloon but inside the balloon they put little blue balloons... and I also got blue and pink cupcakes... so they chose the color of the cupcake they thought it was and when we were ready we popped the ballon and revealed it to them.
Gender reveal cakes are fun and tasty! It's a normal cake with white or another gender neuteral coloured icing, and the inside is dyed either pink or blue! So cute. :)