About T-Shirt Design
You do not have to think too hard about Don't be jealous just cuz i'm a little cooler! T-Shirt. The joke is right there and it gets the point across fast. 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 birthdays or holidays, especially if the person already likes this kind of humor. The sarcastic t shirt vibe is there without making the design feel too mean or over the top. Fans of sarcasm shirts will probably like that the joke is direct and not too polished. The design is easy to get, easy to gift, and easy to wear without overthinking it.