In Book 1, when the trio are on their way down to the Philosopher's Stone, Hermione needed to start a fire(for a reason i cant remember), and she said "If only i had some wood" and Ron yelled at her "ARE YOU CRAZY? ARE YOU A WITCH OR NOT!?"

In Book 7, the trio needed to get past the Whomping willow into the tunnel, and Ron said "If only we had Crookshanks so he could press the knot" - Hermione yell at Ron "ARE YOU CRAZY? ARE YOU A WIZARD OR NOT!?"

i know that's so dumb but i nearly peed the bed while finding that out.