If you put your hands out of the covers at night, then ghosts will come and take your hands and give you ghost hands.
A childhood belief about ghosts

others believed things like this
- I used to think that when it rained,it meant God was washing his hands Anon
- I believed you could dry your hands with hot water, until i got a chance to try it.— A A RENN
- I used to believe that cheerleaders didn't have hands, just pom-poms where they should be!Anon
- I used to believe that a hamburger was called a "handburger" because you ate it using your hands. — ELEKTRA
- I thought chicken's feet were witch's hands — Edward
- When i was a child i used to believe that i became invisible when i covered my hands with my eyes.
— Owen