Oops.
I’m doing some server work, and I accidentally reconfigured one of the servers to use Spanish. I set up the locale just as you’d expect:
locale-gen “es_US.UTF-8”
As anyone can see, there’s a typo in that command. “es” is the language code for Spanish… I meant “en” for English. It took me a few minutes to figure out why suddenly all of the text from commands was being shown in Spanish…