Pain relief. When Jacqui my late wife had hers out she got quite tetchy (and if you knew Jacqui you would know this is somewhat akin to describing a nuclear explosion as a "rather loud bang") with the doctors and nurses who would not give her more than she was allowed, and indeed with me when I did not succeed in bullying them into providing it.

So if you have a secret stock of heavy duties, make sure a friend you can trust has them and keeps them to hand where the professionals can't stop you getting at them.