Take the fitted sheet by opposite fitted corners on the same side of the sheet.
Step2
Turn the corners inside out. (Don't worry about the rest of the sheet; it will follow the corners.)
Step3
Put your hands into the corners. Put the right hand corner onto the left hand corner and turn both right side out. Leave those two corners on your left hand and grab the other two fitted corners. (They will be together, I promise)
Step4
Take the two free fitted corners and fold them on each other like the first two. Then fold them onto the first two.
Step5
Take all four fitted corners by the top of the seam (opposite the elastic)in your left hand. Take the bottom of the sheet and hold it in your right hand allowing the excess fabric in your right hand to fold in toward you so that you have an even line from one hand to the other.
Step6
Take your hands and put them together, grab the fitted corners in your right hand. You now have an even enough square to make a neatly folded fitted sheet.
Tips & Warnings
This technique works with either hand. I am right handed so that is how I fold. For you left handers, just switch hands. This also works with water bed sheets. You just have the added complication of the attached flat sheet.
Don't let anyone catch you doing this or you will never have help folding your fitted sheets every again.