Gender reveal party!!! 💙🎀 (long post)

Our party is all ready to go except for one thing.... I sent out invites and got all of the decorations but I have no idea how we should reveal the gender! I really want to do the paint thing but I need to figure out a way to do it without anyone at all knowing. I was going to have my best friend who's helping plan the party be the only one to know but when my mom found out someone would know before her she literally about lost her damn mind. I really don't want to do a cake because I feel that's over done but I don't know how to pull off the paint without anyone knowing. And I cannot trust my mom to know. I asked her to keep my pregnancy a secret and she told my brother, my uncle, my cousin and all her co workers! And I know I should do what I want and not worry about what she thinks but that's SO much easier said than done.