For me, this is one of those activities that go in the category of "things you can only do when you're married". It's awesome being part of an exclusive club of married folks who keep sex sacred and honor their marriage covenants.
Here's a quick all the fun and none of the guilt idea for a date night, or for any time you have married sex and want to do something silly and fun.
Glow in the dark lipstick!
Yes! it does exist. It's usually sold around Halloween time, but you may still be able to find it at your local supermarket or party store. It goes on clear and doesn't show until you turn the lights off.
Put it on your lips, draw in your eyes and nose. If it's safe to put on your lips, it's safe to put on any other part of your body. It really does work and is cheap! If you want to spend a little more, there are other glow in the dark makeup products too.
Use your imagination. Most importantly, do it together.