Question

How could a man go outside in the pouring rain with outside protection and not have a hair on his head get wet.

This is tricky question.​

Answer 1

Because he had no hair so his hair did not get wet.

Actually your question is wrong the question was "A man went outside in the pouring rain with no protection, but not a hair on his head got wet. How come?"

Answer 2

Buddy I like this and hello.

Because that man doesn't have his hair left but he his wearing wig to protect his head from getting wet.