Suppose you have a cat, Schrödinger's Cat, that's in a box with a radioactive atom about to decay. According to the famous thought experiment, as long as you don't open the box and observe the cat, it's both alive and dead at the same time. But if you do open it, the cat collapses into a definite state of being either alive or dead. This is the paradoxical nature of superposition and the observer effect.
Or, as I like to call it, cat-astrophysics.
Learn more about EPR paradox and Schrödinger's cat in the world of quantum mechanics
Madame Cupcake: The Quantum Baker has some sweet treats for you