My husband and I have this game.
We're not always playing it... and yet we are. The goal is to be as stealthy as possible, to be wily and artful and devious, to really sneak up on the other person, and when they least expect it, express your heartfelt love!
Recent ploys have gone something like this:
"I don't know if you had heard... I was reading this online today and I love you."
"Hey! I know you're tired right now and you just settled in, but I needed to ask you something important, something you might not want to hear, but it's important to me. [Serious silence.] Who do I love?" He knows the routine: "You love me!" And I always reply, "That's right, Joshi. I love you. You're the only one for me."
"Honey!! What time is it?!? I just remembered-- I love you!"
"Ugh. I have such a headache right now. Would you do me a favor? [as he reaches for my water glass] Could you tell me who I love?" Yeah, and then we have the same conversation: "You love me!" "That's right. I love you. You're the only one for me."
Winner and loser? Well, I think we're tied :)