I had a tube with caps on both end for my first hydrometer. I took them both out to clean after my maiden batch, and very carefully slid the hydrometer back in, let it go, and watched seemingly in slow motion as it slid out the other end and smashed on the counter. Pretty bad when the little voice in your head says, "you're an idiot."
Also broke two floating thermometers, and the voice told me to stop buying glass equipment. Tho my new hydrometer has made it thru 9 batches, I only use it for FG. Have a refractor meter for OG now.