The HypnoMario Bros. tee design is for the Futurama fans and Super Mario Bros. Fans.
The concept is simple, funny and self explanatory mash up. Rather than a plain ole boring frog suit that Mario and Luigi would wear to give let them swim faster, jump higher, swim through water currents and hop while on land, this suit presumably gives them the powers of the Hypnotoad.
As for the artwork, it appropriately represents both franchises well. The Hypnotoad eyes are done well enough. The colors work on any Fabric color thanks to the White stroke around the suit that makes it stand out on darker color fabrics. Everything else is taken from Super Mario Bros. 3 such as the font styling, the pose and Mario's face. There is no shading but it really isn't needed, even thoguh it would had been nice to see the extra detail.
This funny shirt is good for those who miss Futurama and have fond memories or moments playing any Super Mario Bros. game.