Let's kick it off with an example. Assume someone asks you: "Why do you think/believe elephants are smaller than mosquitoes?"
Whilst you have never claimed that you actually think/believe that.
The interrogator has hereby claimed that you claimed to think/believe elephants are smaller than mosquitoes, on unfounded grounds.
I am trying to find out whether this is a fallacy or not, if so, does it have a specific name? If it is a fallacy, is it formal or informal?
So far this reminds me of the existential fallacy (the non-existence of my claim of thought/belief, which this question seems to point to).