To hide my ignorance
You look like your thinking hard enough so you must have some of the answer
Just maintain unwavering eye contact with them, and based on what type of student you are they will assume that either you easily know the answer, and aren’t a great person to ask, because teachers like using wrong or only partially right answers to go in depth. Or two, they will assume you have literally no fvcking idea and they shouldn’t even bother. I went an entire year in high school without being called out by a teacher once with this strat
If the teacher calls you just ask them why, if they know the answer, are they asking you. Has never worked for me but may you'll have better luck.