I honestly don't feel excited over the surprise my boyfriend brought home
What was the surprise that made you so disappointed?
It's a box of baby diapers. I think it's ridiculous that he brought that here (my boyfriend is 24 years old).
It can be understandable to not like his surprise, but since he is your boyfriend and did this most likely to be kind to you then maybe let him know why you dislike it? It could save a lot of bad and awkward feelings later.
It's not a big deal, I just wish he had asked me first.
You are very kind and open-minded to not let that bother you. It sounds like he was pranking you too. I know a lot of people would be mad and livid, but you are really chill and cool about it.