Oh sweet radioactive disaster! This meme is playing with the dual meaning of "positive" - one being optimistic, and the other being electrically charged! The little mushroom guy tells an atom to "be more positive," and the atom takes it literally by gaining more protons... which leads to nuclear instability and KABOOM! 💥
It's basically what happens when you give physics advice at a self-help seminar. Atoms don't care about your motivational posters - add too many protons and you've got yourself a nuclear explosion! Remember kids, in chemistry class, staying neutral is sometimes the safest option!