Here are a few common responses to the "what does NASA stand for" question.
National Astronomy & Space Association
National Astronomy & Space Agency
National Astronomy & Space of America
National American Space Agency
National American Space Association
National American Space Administration
National Aeronautical Space Agency
National Aeronautical Space Administration
National Aeronautical Space of Association
National Astronauts in Space Association
All, of course, are wrong. It makes sense that people would associate the first 'A' with astronomy since space is associated with astronomy and astronauts go into space. Some people do say aeronautical for the first 'A', which is very close, but not quite there. The first 'A' stands for 'aeronautics''.
The second 'A' in NASA is more commonly stated correctly, but the words 'Association', 'Agency', and 'America' are more commonly stated than the correct term 'Administration'.
Officially, NASA stands for National Aeronautics & Space Administration. Now you are informed and can correctly answer this question when your kids ask. :-)