(Excerpt from Slate explainer
article)
"If your eyeballs fall out of their sockets repeatedly, you might be a candidate for a lateral tarsorrhaphy-in which doctors sew up your eyelids part of the way to keep them from opening too wide. You could also learn the following technique for popping your eye back in yourself: First direct your gaze downward. Now pinch and pull your upper eyelid with the thumb and index finger of one hand. Lay a finger from your other hand on the top part of your luxated eyeball, taking care to press only on the insensitive white part. While you continue to hold your eyelid up, push your eyeball gently down and back at the same time until it's part of the way in. Then try to look upwards; if everything goes right your eyeball will rotate under the upper lid and back into its socket."
*Shudders*