A mnemonic which is incredibly useful for those people not mechanically inclined when trying to remember which way tightens or loosens a screw.

"Tightie righty" means turn the screwdriver to the right (ie, clockwise) to tighten.

"Lefty Lucy" means turn the screwdriver to the left (ie, counterclockwise) to loosen.

This little trick also works on most faucets, gas fireplaces and whatnot.

This may not work Down Under. (While I don't really know if it does or not, the preceding sentence falls into the category of TWAJS).

I guess I should have emphasized that this mnemonic works in a generalist sense, for those that don't have to screw often ;-)