We definitely get questions like that here. One of the more recent questions was "What was Jesus' last name?"

You are definitely not alone in feeling "not smart". I very often will tell my DS5, "Wow, that's a good question, I don't really know." If it's something that we can look up, we do it together on the computer. Of course I'm waiting for the day when he realizes that the number of questions I don't know is greater than the number I do know... :-)