Oval vs. Circle

Luke, Max and I were lying in bed this morning, snuggling and enjoying one of our last lazy mornings together before kindergarten.

For no reason, Luke starts studying the space between the bed and my nightstand. Then he proclaims to Max, "Hey Max, your head can fit in here because your head's an oval. Mine won't because it's a circle."

What? Where did that come from and why is he thinking of fitting anyone's head into such a small space?