Mr. Safety says use a recessed receptacle:
https://www.amazon.com/Leviton-689-W...-Residential/d
p/B0012DKBL2

Good choice Mr. Safety, but often there isn't enough room in the box
to use it!

Another option, albeit not real attractive, is to use a weatherproof outlet
cover:

https://www.amazon.com/MM410C-Weathe...or-Receptacle-
Protector/dp/B001JEPX44/ref=sr_1_1

Plug the cord in, close the cover, and nothing it going to fall between the
plug and the outlet, not even rain.

I suppose you could paint the cover to match the wall. Perfect for those
situations where you're constantly dropping pieces of metal on your
electrical outlets.

Anthony Watson
www.watsondiy.com
www.mountainsoftware.com