Not Just The Watermelons That Are Hollow

(I am going grocery shopping with my mum when she stops to pick up a watermelon. To my bemusement, she brings the melon up to her ear and starts hitting the side of it.)

Me: *staring at her* “Um…. what are you doing?”

Mum: “[Uncle] told me this trick with watermelons! You hit it, and you can tell by how it sounds whether or not it’s fresh.”

Me: “So, how is it supposed to sound if it’s fresh?”

Mum: “That’s the thing; I forgot! It either sounds hollow if it’s fresh, or hollow if it’s not. I forgot which one is which!” *continues picking up watermelons and hitting them*

Me: “Well, what’s the point of banging on them all if you don’t know what sound you’re looking for?

Mum: *pauses*

Me: *stares*

Mum: *resumes her assault on the watermelons*

(I’ve given up trying to understand the logic in this woman’s thought processes.)