You will need: one 3 year old boy, one comfy bed, and about an hour of time.
You will imagine that your son will snuggle with you like he did as a baby, and that you will both have a very nice nap together.
What will actually happen is that the boy will lay down very sweetly for about 10 seconds. He will then decide he wants to hide in the covers, and request that you lift them up so that he can do so. Once hidden, he will rapidly wiggle back to the pillow and lay down again. Since you are still trying to sleep, you will tell him that he needs to lay down and have quiet time so you can sleep. He'll respond by telling you that you need to open your mouth, and demonstrate by making snoring noises. If you don't open your mouth, he'll stick his fingers in it and make you open your mouth. Then he'll move on to your eyes, and get really, really close to your face. He'll poke you in the eye so you will look at him, and then he'll laugh and tell you that his eyes are blue and that you have eyebrows and he has eyebrows. Then he'll decide to hide again, and once again wiggle back up to the pillow. At this point he'll tell you he needs a toy to take a nap, and he'll go to the living room and get two tiny Dimetrodon (sp?) dinosaurs that he got for his birthday. This will take him just long enough that you will start to doze. You will soon be awakened by a small dinosaur tail in your nose. At about this point your dog will start scratching on the door of your bedroom, and your son will let him in while he goes on another trip to the living room. You will remember that your dog is an ideal napping partner, as he just curls up by your feet and goes to sleep. Soon your son will return again, and this time he will have a hamburger that he made special for you. This will be given to you in that he will throw it at your (not) sleeping face and tell you that the hamburger came apart, and can Mommy please fix it? Shortly after this point, you will realize that your attempt at a nap was completely futile, and you will give up.