Gender Reveal for Son who REALLY Wants a Brother

Jennifer
Right now, my son has 3 little sisters, and he REALLY wants a brother. (The girls are pretty ok either way.) I want to find out the gender, but if I am having a boy, I'd like to surprise my son with a reveal.
Any ideas on a fun gender reveal for a 10 year old who has been waiting through 4 babies now for a brother?