To go to a softball game you don't have to wear something fancy or dress up like you are going on a date. You can wear anything ranging from formals to semi – formals to out n out casuals. But a more suggested outfit would be to wear the colours of the team that you are going to support at the softball match. Wearing your favourite teams colour will only make more sense, since you are going to the game you will obviously support your favourite team and what other way to show your support then by dawning the colours of the team that you like.
