The other day, I heard a radio comedian wittering about "'Say, what's in this drink?' Well, they didn't have roofies back then." This is true. But they did have "putting several times more alcohol into a mixed drink than one would expect". Or whatever. Clearly, the woman is finding that her drink isn't what she's expecting, and finds it concerning.
Like "Have Some Madeira, M'Dear", this song hasn't aged well.
Though hearing it sung by Ricardo Montalban, my internal response to "what's in this drink?" involves Corinthian leather, coffee, and CREEETURES.