DIY Star Wars Sharpie Light Switch Plate from mmmcrafts here. There is also a really good mug at the link with “This is not the mug you are looking for” on it. First seen at Geek Crafts with more suggestions for the light switch here. I can think of some more that I can’t print.
Can you think of other light/dark on/off phrases people could use?
If you own an image you want taken down please email me at truebluemeandyou [at] gmail [dot] com