I have been turning wrenches as a hobby for close to 20 years, with a few years of part time pro work as well and I have only broken a couple that I can remember.
One that I remember was a cheap made in Taiwan one and I was trying to take a tire off an old trailer my Dad had. Of course he waited until it was -30* out and buried in the snow to move the trailer. The tire was so old it ripped apart, leaving part of it still froze to the ground!
I had a long breaker bar with a 3ft pipe on it and I was jumping up and down on it while my Dad held it on the lug nut. Socket exploded.
Oh, a good one. I broke a 3/4" to 1/2" adapter. Trying to crush the crush sleeve on an 8.8 and it was being a real biotch. Welded the axle to the workbench and had a 3/4" drive breaker bar with an 8ft pipe. 2 200lb+ guys on the end of it.