This duet has been covered by a long list of musical legends, and it sounds great, but the content of the song is more than a little disturbing. In essence, it is a song about sexual coercion and, possibly, rape.
In the song, the female character is trying to leave her partner's home for the night. She comes up with many good reasons to leave, but her partner is insistent that she stay the night, despite her obvious desire to go. You might be tempted to interpret this as coyness. After all, as women, we are not encouraged in our society to be direct when talking about sex. If we say no, we are frigid prudes. If we say yes, we are whores. But even if you choose to interpret their back and forth as an innocent game, the innocence flees instantly in this lyric:
"Say, what's in this drink?"
It could simply be a delicious beverage that causes her to wonder about the ingredients but, in context, it is more likely either a much stronger drink than she expected or it has an ingredient that she did not agree to having added. Both of those suggestions lead the listener to believe that she is being chemically manipulated into staying against her will. It doesn't exactly put us in the mood for Christmas.
Before you call us oversensitive feminists, check out this article - "8 Romantic Songs You Didn't Know Were About Rape." We're not the only ones who noticed.