You and your Partner: secret super-spies.
The next social gathering that you both attend: a Mission.
While out in public (perhaps en route to Mission) listen for Code Words. When you overhear a seemingly random phrase that sounds like it might be your Code Words, confirm it with your Partner. Then, your Partner does the same. Each of you arrives at the Mission with personal Code Words.
Give the Code Words as a sign-without tipping your hand to Enemy Agents, who are everywhere.
Mingle at the gathering within earshot of your Partner. Work your Code Words naturally into conversation. If the person you're speaking to treats the Code Words as normal, you've successfully given the sign to a Contact. Give the Contact the Agency-approved confirmation signal (a friendly smile).
If the person you're speaking to reacts as if the Code Words/your behavior are odd, you've been caught by an Enemy Agent! Your Partner steps in to cover for you while you find a quiet corner of the gathering and whisper into your watch (or microchip embedded in your wrist) "Cover blown, extraction requested."
If both of you keep your cover, whoever gave Code Words to the most Contacts wins.
Playing with the idea of unwitting game participants here, in the vein of Vincent Baker’s The Vengeful Demon of the Ring. If you play it, I’d love to hear about it! Message me on Twitter at @ClovenPineGames