so a colleague recently asked me if I could think of a book or film in which Aliens had taken over human minds, but some people resisted, and could identify each other by tapping out rhythms.
so of course, we both resorted to asking our favourite LLM tools - he asked ChatGPT, and I asked Bard.
In both cases, highly "confident" answers came back, in most cases, rather plausible - for example
Heinlein's Puppet Masters,
Carpenter's They Live (and less plausibly, The Thing)
Invasion of the Body Snatchers
The 2005 film of The War of the Worlds
So of course, the body snatchers didn't take over human minds, they replaced humans.
The War of the Worlds is a bit daft given the aliens are in giant tripod machines
The Puppet Masters doesn't really work as the aliens are physically attached to humans.
The Matrix is just plain nonsense. And The Thing is daft as it doesn't take over human minds, the thing replaces/mimics people (and dogs)
So that left They Live, which is a veyr cool film, and Bard even made up a fairly detailed scenario where the main nameless character (called Nada in the credits) signals to others by tapping his feet (fact is that the film is based around special glasses that let you directly see who is an alien, and also what subliminal messages they are saying, so this too is a bullshit answer - for more about bullshit, see this excellent philosopher's essay )
In the end, I tried simply googling, and got this Dr Who episode - which looks and sounds plausible, as the description is written by humans (as far as I can tell, and definitely not Daleks).