Hard to answer that one, I don't often break things unless I meant to.
Discounting things like bent saw blades when cutting cast iron pipes, probably the time I opened the door to a small cupboard in my back breezeway only to find it wasn't properly attached to the wall. I caught the cupboard before it fell to the ground but my wife had an ornament sitting on the top that wasn't so lucky.
Thankfully the ornament recovered with the application of a small amount of glue, and it was a cheap from the local thrift store.