I say thank you because you can't fix stupid
that response is easiest & least annoying.
if i had a minute, i might say, "do you know that some of the best pictures were taken with cheap cameras? photographers first analyze lighting, perspective & then adjust the camera to create art. cameras are technical paint brushes for artists who can't paint."
the funny & true analogies in this thread (car, mouth...) would be lost on them because they don't think! the lack of "critical thinking" of most Americans is beyond crisis level. we can list contributing factors ad nauseam, but sometimes Dilbert is right!
a consultant with whom i worked said that in grad engineering school, he took an aptitude test about thinking. the result was plotted in one of 4 quadrants:
y axis: "concrete" and above, "conceptual"
x axis: "random" and to the right, "serial"
he went to the prof and said, "this test is great"
prof said, "your score was in the 4th quadrant, right?" (the upper right; conceptual & serial)
"yes, how did you know?"
"because people who score there are the only ones who think so!
so, yes, in a way you can't fix stupid.
plant a seed, they might ask for water.
but, the alternative is tempting.
Snappy Answers to Stupid Questions