Like some of the previous posters here, I've never been in a position to "offer" my wife. We've always 'kinda known when something is going to happen, like she'll be subtly touching him or even making out with him at a party. She more or less offers herself to him and we just let events unfold whether that means finding an empty bedroom at a party, or taking him home with us. My role is always the same: facilitate her lovemaking with the lucky guy (usually someone we know) and enjoy what is happening as much as possible.