Macintosh Plus is an alias of the electronic musician Vektroid. This T-shirt has the aesthetic motif of the cover from the album Floral Shoppe. The album was released by the artist in 2011, and according to some sparked the aesthetic movement known as vaporwave.
Look how happy this guy is because he has this cool t-shirt. If you buy this t-shirt, you will probably smile like him. Even if you don't, you will look pretty cool.