I need a funny but not too informal response to my professor?

There was a typo in his email response and he said "I'm (professor s name) iPhone 6 and i take responsibility for any typos or errors. Its not his fault. Seriously.

I just emailed him about the price of the textbook so i haven't met him yet but i thought it hes response was funny

I don't think you should respond to his joke. Just accept it, he already knows it's funny, and it covers his bleep.

Do not point of the typo in a humorous or other manner if you want to stay in the teacher's good graces. If the typo made his answer unclear, you may verify the answer, but don't point out the mistake. No professor likes a smart ***.