If you have a standard duvet cover, which has an opening at the bottom, or foot end... grab the two corners at the top (pillow end) of the duvet with your right

If you have a standard duvet cover, which has an opening at the bottom, or foot end... grab the two corners at the top (pillow end) of the duvet with your right hand, pull the top middle center to your right hand, which is holding the corners, so that it now holds the center and two top corners, then reach your right hand inside the duvet cover to the top center of the duvet cover. With your left hand grab the left-hand top corner of the cover and with your right hand, pass the left-hand top corner of the duvet to your left hand so that it holds both the cover and duvet at the corner. Move your right hand to the top right corner of the cover and then pass the right corner to your left hand so that it now holds both corners. Move the right hand out of the cover so that it can grab the right corner from the outside. Spread your arms apart so that the top of the duvet rises up inside the top edge of the cover. Shake and wave, toss onto the bed and then pull the corners of the cover down over the duvet, button or tie off as needed.