I learned two big things while on the wards:

1) The medical record is an amazingly powerful and legally binding document that you should not take lightly. It is permanent. Things on it can never be deleted.

2) Nurses are just amazing and powerful as the medical record, and if you piss one off they can use the medical record against you.

Here is an actual example I read of said power in use:

PATIENT IS NOW MORE CO-OPERATIVE; HE ALLOWED US TO START HIS IV AND HE WANTED A 'CONDOM' CATHETER WE TRIED TO PLACE ONE BUT IT COULD NOT FIT; HIS PENIS IS VERY SMALL.

Moral: Don't piss off your nurse.