Gift that keeps on Giving and Giving and Giving.
When you take your wife/girlfriend to a swingers party or gangbang. It's considered a "Gift" that keeps on giving even when you're done having sex with her. There are other people around to keep giving it to her.
Yea, for Valentine's Day I brought my wife to a swingers party and that's a "Gift that keeps on Giving and Giving and Giving...."