This design is inspired by the amazing existential loop in which almost every character of Adventure Time is involved. Everyone has been someone else, in the past or in the future, but their Universe (and perhaps also ours) always represents itself with the same combination of paths and the same selection of solutions. Only those who are immortal can slightly see the pattern: our Marceline, for example; and that’s why, maybe meanwhile floating sweetly in the air, she can play us a music that can remind us who we were and who we are in an infinite loop of sensations.
(Ah, there is also another hidden meaning in the design: there is an association between the vampire bite on the neck of Marceline (two dots, two circles) and the system Moon-Earth, if you notice maybe also them are just two little dots in a even greater story.)
PS: if you like the design you can vote it and help it to become a real product on Threadless with this link: https://www.threadless.com/designs/everything-stays-10