I need ideas on how to reveal the gender of baby at my boyfriends birthday dinner


So I find out what I'm having soon my so keeps saying it's a boy ( we already have 2 boys) I think it's a girl lol anyway he wont be able to make it to the anatomy scan 😩 but his birthday is the Saturday after I would like to figure out a way to reveal the gender of the baby but have no clue how it's not gonna be a big thing it's gonna be s small dinner with a few friends ( I want to surprise him )

Any ideas ?