Merriam-Webster defines “bull in a china shop” as “a person who breaks things or who often makes mistakes or causes damage in situations that require careful thinking or behavior.”
But Mythbusters actually let a bull loose in a china shop and learned that bulls are . . . “very careful” of the china. When the team released more and more bulls amidst the shelving, the bulls just continued to diligently avoid bumping into anything:
(Via Robin Sloan and lenazun.)