I just know that I'm about to have the same problem today!
Looks like its going to be a sunny day today, so time to pop my enormous
Queen size! Duvet cover into my washing machine, hang it on the line to dry, (the Duvet cover, not the washing machine!), then struggle in vain to feed the cover back over the fluffy interior stuff.
Much time will be spent crawling inside the cover to locate the various corners....
...I may be some time....

...!
A process best carried out on alternate Leap Years...
..trust me...

...!
Paul....lost in the midst of Duvets...

...!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.