Depends how high, at the worst you can fall at 60mph to the ground without anything and it would be like being in a car wreck! a tiny bed sheet would not save you from bodily harm, the reason why is that there is not enough surface area on the bed sheet to provide sufficient air resistance to slow your fall enough to where it is a safe landing. in other words the bed sheet will slow you down to maybe 59.5mph but only if it doesn't rip from air resistance. this is why parachutes are huge and need to be folded properly in their backpacks in order to open properly and SLOW YOU DOWN. Absolutely no. I suggest you don't try it for different reasons. First off the material let the air flow through it, wich won't slow your fall. Secondly, depending on your weight and size, your sheet would need to be 2 or 3 times the size of Kingsize bed.
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