He presents the necklace to her with a small smile and a modest, "Just thought you'd like something to hang my tag from." He slips the chain over her head, then pulls his own tags out from under his shirt, one of gold, one of steel, to show her. She digs his liberated tag out of her pocket and quickly fastens its little chain around the larger one. He grins at the equal but opposite nature of their dog tags and helps her slip hers under her shirt. She lets out a squeak as the cold metal touches her skin.
And then she kisses him to make him stop laughing.