Have him have a diaper party. It was my fiancés way of celebrating him as a dad and we got a crap ton of diapers! Babies only 7 months old and Ive only bought 2 boxes! He had so much fun with his friends and they all got pretty drunk!
Im doing lots of games to include the men like having the couples dress each other as babies or have them guess baby food flavors. The guys love those esp making each other eat gross foods and filming it
The matching shirts is a good idea, but is it something is he is constantly bringing up? It should be both of yours day, but a baby shower is really mostly for the mother, He sounds jealous tbh..
tell him to have a diaper party with his friends, where they sit around shoot the shit, play video games if they into that and drink beers... at a baby shower the soon to be mom is the center of attention.