|Instead of allowing your manager to put you on the spot, put yourself on the spot first. It is possible that he is calling on you because he believes that you are not prepared, and he is taking this action to induce you to do more homework.|
Prior to these meetings, you should do some additional planning and preparation. If you received an agenda in advance, look it over carefully, try to come up with as many difficult questions as possible, and then try to come up with excellent answers to each. When you have these answers, consider practicing them so that you can get right to the heart of the matter if the question arises.
If your manager senses that you are on top of your game, there can be some interesting outcomes, all of which work in your favor. If he continues to ask you questions, you can demonstrate your knowledge and insight. Or, he may stop asking you questions because he recognizes that the grilling is no longer needed. Either way, he is likely to provide answers to some of the questions that you have about him.