Setting: 3 year old son, squinting his eyes really, really tightly.
Son: "Mo-omm (said in a sing-songy way). Can you see me?"
Me: "Yes, dear boy. I can see you."
Son: "No you can't."
Me: "Actually, yes I can."
Son: "No. My eyes are closed so you can't."
Me: "Right. I forgot."
Mental note to self: It might be time to take a course on "Playing Along with an Imaginative Child" and "How not to Crush your child's enthusiasm for Play".