While there’s a snowball’s chance of this actually HAPPENING, and technically if it did it might not even turn up anything untoward (illegal drugs) the meme is important.
Sotto voce message to audience: she’s acting very artificially affected, please notice that!
I see more in the supernatural than the natural to explain this, frankly. Hill and Bill are the Witch and Warlock Marriage Made In Hell. It would not show up on a literal drug test.
Except that witchcraft doesn’t work against truth. (Very important principle to learn.)