Why do they have to nail down the lid of a coffin?

Seriously, do they think that the dead person's gonna rise from the dead or something?! I'm confused.Why do they have to nail down the lid of a coffin?
They honestly haven't been ';nailed'; down in about 50 years (at least in the Western world). Caskets are closed with a sealing mechanism and a casket ';key';, which is actually a long metal handle that cranks the lid and base together. No nails needed. As for the other answers, grave robbing hasn't been an issue for, oh, about 50 years at least.Why do they have to nail down the lid of a coffin?
1: People have been known to drop coffins or they've rolled out/off of carts, wagons, etc. Having a nailed-down top would presumably keep the body inside.





#2: Lowering a coffin into a deep grave sometimes 'tips' the coffin; if the top isn't nailed down, the body could roll out.





#3: Because the soil removed when digging a grave is loose, if the top wasn't nailed down, a loose/shifted top could allow dirt to sift into the coffin; nailing the top prevents that.





#4: ';just in case'; as previously noted.





#5: ';that was the final nail in his coffin'; is a great descriptor, as in a politician's final mistake, etc.
It is to prevent robbery and perverts from doing bad things to the body.
It's just in case they aren't quite dead yet.
it helps keep the grave robbers out