Well, you got it mostly right, but the lyric “Say, what’s in that drink?” IS about drugging the drink. Slipping a Mickey, aka chloral hydrate, was the 1930’s version of putting rufenal or quaaludes in a drink. It seems to me that the woman is making a faux accusation as a way to acknowledge her feeling of intoxication in the moment. Nonetheless, it does sound creepy.

All in all, I like the song. It harkens back to good old flirting and the game of mutual seduction.