Joe, a quick read of your post indicates that you have had eight (
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balls crack over a period of a few (?) years. Amazing! Assuming you have quite a bunch of balls laying around (don't we all!) let's say 40 over time, then 20% of your balls have cracked, creating the now familiar "pop" you have described.
I do not mean to imply anything but to have 20% of your balls crack is simply amazing!
My balls are not subjected to heat/cold as I live in SE Florida and it rarely gets cold enough to bother anything. My balls are either in the garage or in the car and get really hot at this time of the year.
I have never had a ball crack, even when I lived in Chicago, PA or the Washington DC area.
Guess I am just lucky or perhaps I have not bought enough balls to have a large enough sample, statistically. I think I have about 15 in the garage now.
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Never take a sleeping pill and a laxative on the same night.