This is where we return to my movie audition days, but now I’m a professional. Hold the honeydew in one hand (or two, if it’s hefty). With the other hand, give it a solid thump in the center.
You’re listening for a deep, resonant sound—like a drum, not a click. A hollow “thunk” means the flesh is loose and water-rich, which is good. A high-pitched “ping” means it’s dense and underripe. Warning: this may make you look eccentric in public. Embrace it.