Dealing with someone who asks many questions during presentations While giving a presentation there is one person in the audience (X a PhD student and a friend) asking all sorts of questions, even unrelated ones. They are also eager to answer questions of others while just in the audience. X attends almost every talk in the department (info from colleagues) and shoots out his questions. During my first few weeks I consider this as good academic practice but had to change my opinion when the same occurred during my talk, with  about 7-8 questions asked during a 30 minute talk; some of them were blatantly off topic (like asking why I used this numerical method over the other, which I haven't even heard of). We attended a thesis defense in our department in which the protocol suggests that the defense committee should ask questions first in the time allotted to questions. X couldn't wait, asks during the talk and this annoyed the committee, one of the stood up and asked X to stop! 

I talked with X, and they said they are doing this to push the presenter to their limit and described the thesis committee as a bunch of idiots. X said they were very shy in their school years and worked really hard to reach this level of confidence.

My analysis

Although questions are welcome during the presentation, X seems to ask questions for asking sake. They used to ask questions to compare a certain method or phenomenon with their line of research which the presenter has never even heard of.

How to deal with him if this continues (sure it will!) during one of my presentation? I don't want to offend, as they are one of my few mates on  campus.

Side Note:
X's questions are not dumb questions in reference to some comments. They are sometimes off-topic, sometimes seeking explanation on a particular terminology(during the talk). I feel the questions are being asked simply for the sake of asking a question.
You are not obligated to accept somebody disrupting your talks, particularly when the questions are off-topic and when much of the audience appears to be disapproving.  The basic solution is to act as a moderator for your own talk.


For questions during your talk that you find disruptive, a simple solution is simply to say, in a calm and gentle voice, something like:


  I'm going to defer that question for now.  We can come back to it at the end.

During a question period, if a person is dominating the discussion, you can say something like:


  I think some other people may want to ask questions as well, so I'm going to ask you to hold your questions for a bit while we hear from others.



The key here is to be firm, gentle, and impartial.  Your voice should make it clear that it's not about this particular questioner or about you being defensive, just about keeping on topic.

After you say something like this, most people will leave the question and let you come back to it later.  If the questioner does not, simply repeat yourself, remaining as calm and unruffled as you can, and then move on.  If the person continues to be disruptive after that point, it will be clear that they are making an unusually large problem, and others are likely to help intervene.