Do you have a proven working technique for choosing a good watermelon? You don't just go to the store and pick up the first watermelon you find, do you?
Sure thing, larger supermarkets take it back even after you have cut it and it is not the perfect red, firm, juicy watermelon you wanted, but why not buy the best watermelon in the first place instead of taking an extra trip to the store to return it?
I'm not sure if my technique works, but I generally tap on the watermelon, like knocking on someone's door. If it sounds hollow-ish, it's good enough for me. Unfortunately if the watermelon is sitting on top of a box or something, the hollow sound of the box is probably what we hear and it is mistakenly taken for the sound of the watermelon itself and what you end up getting is good for making morrabbaa (jam).
I have seen folks bangging on the watermelon, like they're slapping someone. I tried that technique and it was actually pretty painful. You can even injure your wrist because you have to slap it real hard; the loud noise attracts too much attention!
Others squeeze both ends with their hands; if they hear a cracking noise, the watermelon is good. This technique is doable if applied to smaller watermelons that little guys like me can handle. Lifting a big watermelon and squeezing it at the same time is a job for Herkool (Hercules) and not very practical. I once squeezed one too hard; it was one of these yellow watermelons and I didn't realize they could be more delicate than the red variety. It broke and I got juice all over my face, shirt, pants, and shoes.
We were once coming back from Santa Cruz, not far from San Francisco, and on our way back, we stopped to get some fresh fruit. We saw a guy holding a watermelon between his legs — yes between his leg, about his knees. I honestly thought he was either exercising or demonstrating something, at least that's how it looked. Instead of squeezing the ends with his hands, he was squeezing with his legs, while knocking on it. The guy looked Pakistani or Indian – I wish I had photographed him. I cannot imagine myself holding a watermelon between my legs and knocking on it in a supermarket.
When I was younger, I remember one of our neighbors was quick to sit on a watermelon. Come to think of it, sitting on a cold watermelon, in the middle of the summer, is a little kinky, but using her hip power (weight?) worked for her. If you recall, we hardly ever bought watermelons from the store. They were generally sold atop 3-wheel mopeds — motor sehcharkheh — or, on those 4-wheel carts selling watermelon in the summer, and laboo (boiled beets) in winter.
I remember the watermelon seller would always, ALWAYS, make a little comment like “Khaanoom, befarmaayeen injaa besheneen”, [“Lady, sit on this”] implicitly pointing at his you know what, which I am sure she always heard but pretended she didn't and always asked: “Bebakhsheed nashneedam chee gofteen!” [sorry, didn't hear what you said]
I'm not sure how effective any of the watermelon testing techniques are. Watermelons in the U.S. generally taste good and no pre-testing is required. That's not how they think in Iran.
We went on a brief trip to Iran a few years ago and while there, I went grocery shopping with my father. The old maydoon fruit market had now moved up north from the southern, rundown parts of the city. There are in fact a couple of branches at different locations in Tehran, like Price Clubs for fresh produce. Instead of buying from the local convenient store, like we used to, a lot of people go to these maydoons and buy fruit and vegetables particularly for parties and events.
We were looking for the right peaches and cherries and grapes. As we went from one stand to another, I saw an interesting looking guy, whom I first thought was dressed in traditional Kurdish clothes (my father corrected me: he was from Afghanistan). He picked up a watermelon, put it on his head, and a moment later he fell to the ground. The watermelon, which indeed was a gorgeous red inside, fell to the ground with him, burst open and splashed all over him and everyone around. People quickly gathered and helped him come about.
Apparently the Afghani Technique is to put the watermelon on your head and squeeze downward. You either have a ripe skull with questionable content or a ripe watermelon, and a skull, still with questionable content.