I have a deal with my 8 yr old

So I’m 36+6 days with my 4th daughter. My 8 yr old is convinced it’s a boy, convinced. I show her the ultrasound and she simply tells me he’s hiding his junk and that’s why you can’t see it 😂 which I mean is possible even the tech said she was only 60% sure, but I doubt it. So we have a deal that if baby is born girl she has to get me a chocolate milkshake and if baby is born a boy I have to get her a mint milkshake 😂