It’s not rocket surgery.

Stand up with the sheet.

Place your hands inside two adjacent corners so the elastic is at your wrists.

Bring your hands together, folding the sheet in half, and flip one corner over the other hand so that one is tucked in the other.

With your free hand, reach down and gather the other two ends which are not tucked.

Let go of the tucked corners, which will slip apart again.

Curse the gods, and then roll the crumpled mess between your arms until it’s small enough to stuff into a closet or drawer.

Profit.