Look into someone’s eyes when you don’t trust their answer
If you ask someone a question, and don’t like or understand their answer – look into their eyes and just pause instead of asking more questions. This will make them feel a little pressured, and they will then be compelled to explain or elaborate on whatever they just said.
Us humans are highly sensitive to even the most subtle social cues, and prolonged eye contact in this kind of situation subconsciously communicates to the other person that you’re not happy with their answer – without you having to say so.