Dexter told Delilah that she should always help Mom fold the sheets. The king size sheets for the big bed are very difficult for one person to fold alone. So Mom always needs to lay them on the floor. He told Delilah that Mom always appreciates it when he helps her. He is sure that by rolling around and chasing imaginary critters in the fitted corners helps to flatten the sheet so that it can be folded more easily.
Dexter told Delilah that the fun starts even before Mom starts to fold. When she piles the warm sheets from the dryer on the chair, it's really cool to jump onto the chair and burrow under the warm sheets. No one knows that you are under there. It is so private like being in a cave.