Do you have a continually loose screw? I'm not talking about the one in your head, I am talking about one in a cupboard or drawer that you seem to always be tightening?
If so, then you probably have a simple fix in your bathroom cupboard. A bottle of nail polish.
Remove the screw and then dab the inside of the hole with some nail polish, let it set for a moment so it is soft, but not runny and re-insert the screw.
The half dried nail polish should make the screw set in tighter, and then when it is set it should keep the screw from loosening again.