Do floating thermometers count? I broke mine because I am stupid, I had it in the wort while I was using my immersion chiller and I was stirring to distribute the heat to the IC... craaaack. In the wort. Not cool.
Also, I had a hydrometer testing cylinder that I managed to break... a while ago, I had left some beer in it, and SWMBO thought it'd be a good idea to pour it out, leaving a sticky residue that clouded up the bottom of the cylinder. I never bothered with it but today I got fed up seeing it so I poured acetone into the plastic cylinder. Every part the acetone touched basically cracked and lost all integrity, so I could crush it with barely a tap. Also, when I poured out the acetone it left a weird white residue all inside of the cylinder, which I am guessing was the degraded plastic.
Primary - 1 Gal JAOM, Belgian IPA, Pumpkin ale
Secondary - 5-way split Breakfast Imperial Stout, 2 Gal Traditional mead
Bottled - Kolsch, Pliny the Younger clone, Centennial Blonde, Alpine's Nelson clone, Apfelwein, QuicknDirty Cider
On deck - EdWort's Haus Pale