They can be in a group of people and say "Hey, want to 'have fun' later?" with a wink and know what the other is really wanting. They can say it in front of the friends, "Honey, I just want to have some fun" and the kids will just think you are planning to do something fun- which you really are.
I love the code phrases and words for a few reasons. It allows you to say what you really want without making yourself completely vulnerable and having to say the "s" word if that's out of your comfort zone. It allows your partner to get excited and look forward to something. It gives you something secretive and romantic to share with each other that others won't have a clue about.
Do you have any code words or phrases?
How do you hint that you're in the mood?