Well, on second thought....
If the assignment shows the due date, or the syllabus shows the due date of the assignment, it's kind of stupid to ask about the due date.
If the syllabus clearly states how much a certain assignment is worth (that is, if the syllabus isn't confusing), then it's kind of stupid to ask how much that assignment is worth.
If the syllabus says you have to use APA style on your papers, it's kind of stupid to ask if you have to use APA style on your papers.
If the textbook says exactly how many pounds of plankton a whale eats each day, it's kind of stupid to ask how many pounds of plankton a whale eats each day.
These are examples of stupid questions, and they're stupid because the answers are clear and are staring you in the face, if only you'd take a moment to look in your class materials.
And yet countless teachers go on insisting that "there's no such thing as a stupid question." They mean well, but don't take their word for it. Or maybe you can try this one: after you miss a class due to an absence, ask your teacher if you missed anything. ("Of course not - since you weren't here we decided to cancel class.") What we really want to say by telling you "there's no such thing..." is that if you're confused about something, don't let your embarrassment about asking stop you from asking.
For example, if you don't fully understand what the textbook says when it describes something, you should ask, and it's not a stupid question. You might think it makes you look stupid, but you can usually count on two things: 1) someone else in class was thinking the same thing and is glad you asked; and 2) the teacher will treat you with respect. (Besides, if you really are playing with only half a deck, the teacher will see that on tests, so what's the use trying to hide it for the sake of an image in class?)
Of course, there are those ruthless fellow students. The ones who roll their eyes, giggle, and then try to trip you when you walk down the hall just to show that they think you're dense. Or did that all come to an end in high school? College students are usually much more tolerant of each other. In fact, I think college students are more likely to rag on the teacher for having made someone look stupid, than they are to take advantage of your weaknesses like the kids used to do in middle and high school.
Back to our topic... teachers also like to say, "the only stupid question is the one that's not asked." Well, if it turns out to be one of the stupid questions (see above), then unless you've lost the syllabus or assignment instructions, don't ask it. Look it up. What we really mean is that it's stupid to be confused by something and not ask for clarification. After all, college isn't absorption and knowing it all... it's inquiry. People come to college to learn, and they learn by asking questions. And you can bet that smart people ask more questions than dumb people. After all, they're smart... they know it's good to ask questions in college, especially questions about anything they find confusing.
And then there are simple questions. These aren't stupid; they're the ones that seem like they're just too easy to be worth asking, or they seem so simple that if you don't know the answer already you must be stupid. That's a mistake. That's where holding back and not asking can hurt. Just because some question sounds simple to you doesn't mean that it's something you should already know. It might or might not be easy to answer. A really simple question is simple because it's easy to answer. Sometimes, though, simple questions aren't simple at all - they're very hard to answer. But still, you never know until you try, and there's no harm asking the simple questions because they're not inherently stupid.