It is likely that at some point in your life, someone has said to you that, "There are no stupid questions". That person was probably trying to make you feel at ease in a learning environment.
Unfortunately that person was incorrect. Possibly they didn't know any better. But the truth is, there is most definitely such a thing as a "stupid question".
A stupid question is a question that is asked with the intent to halt discussion and interfere with learning. It is asked with the intent to belittle the subject at hand and the person talking about that subject. Stupid questions are used make black insinuations about the receiver's character and morals.
The person asking the stupid question will defend him or herself by saying, "It's just a question" or "Don't be so touchy" or "Why are you taking this so personally?"
"When did you stop beating your wife?" This is an excellent example of a stupid question. It impugns the recipient's moral character, and forces the recipient to take the time to unpack the question, dissect it and answer it. It could be an excellent "drive by" question that would derail any conversation. It is never asked in the spirit of conversation or learning. It is never asked by someone seeking truth.
"Were you there?" This is a favorite question of creationists. This isn't just an example of a stupid question, it is a very common question that pops up in discussions with creationists all the time.
Like any stupid question, the person asking the question is not looking for any sort of answer that increases knowledge or seeks truth. Instead, the creationist asking this question is trying to shut down the conversation in order to declare victory over the other person.
Again, a stupid question is asked in order to stop the discussion. And in order to answer the question, it must be unpacked, examined on its own and then answered. Which of course derails the conversation - which accomplishes the questioner's goal.
Creationists love this tactic of asking stupid questions so much that they actually instruct school children to ask these questions in science class.
Don't allow yourself to be tricked into asking a stupid question by people with an agenda. Instead, learn how to ask smart questions. Ask a question that is designed to elicit further explanation, to encourage teaching, to enhance your own learning.
Ask, "How do you know?" That is a smart question.