So let’s talk about that drink. I’ve discussed solely looking at the lyrics of the song and its internal universe so far, but I think that the line “Say, what’s in this drink” needs to be explained in a broader context to refute the idea that he spiked her drink. “Say, what’s in this drink” is a well-used phrase that was common in movies of the time period and isn’t really used in the same manner any longer. The phrase generally referred to someone saying or doing something they thought they wouldn’t in normal circumstances; it’s a nod to the idea that alcohol is “making” them do something unusual. But the joke is almost always that there is nothing in the drink. The drink is the excuse. The drink is the shield someone gets to hold up in front of them to protect from criticism. And it’s not just used in these sort of romantic situations. I’ve heard it in many investigation type scenes where the stoolpigeon character is giving up bits of information they’re supposed to be protecting, in screwball comedies where someone is making a fool of themselves, and, yes, in romantic movies where someone is experiencing feelings they are not supposed to have.