About T-Shirt Design
The joke on Best Mimi Ever T Shirt is easy to understand, and that is a big part of why it works. It has a clear everyday humor vibe, which makes it easy to picture as a gift or something to wear for fun.
It makes sense for holidays or birthdays, especially if the person already likes this kind of humor. As a novelty t shirt, it has a simple idea that is easy to notice without feeling overdone. It has the same easy attitude people usually want from sarcasm shirts without sounding forced. The whole point is to get a laugh, and the shirt does that without making things complicated.