It's pretty hard to explain without a ton of self-deprecation. But, after 22 years of marriage, there's not much modesty left so...
I had my 3-point BH (I know, I know, they're the evil spawn of Satan) connected, and somehow when I hooked it up, it was way out of level. The right side was up about 4" higher than the left. I didn't use it that way - I had just attached after finishing work at a neighbors house, and wasn't on level ground.
When I saw it the next day, I thought, "That doesn't look right, I need to level that." So, I proceeded to use the hydraulics on the BH to level it WITHOUT first removing the lower arm swing pins. I got it level, dangit, but the tractor did not like it. Just a little more on the right side... SNAP!
It took a second to realize what made the sound. But as soon as I found the pin bent back, I realized what I'd done. By raising the right side with the BH levelers, it was forcing the locked-in-position left arm down. But with the pin firmly in place, the arm couldn't swing. Instead, it bound up, and the pin at the transmission was the weakest link. Total bonehead move. If I'd removed the swing pin from both sides before trying to adjust the level, this lesson would never have been learned.