What is a command you accidentally taught your pet?
My goldendoodle puppy doesn't ever want to come back inside. I told my beagle "go get your sister" as I tried rounding up the puppy. Now when I say "go get your sister" the beagle runs to the puppy and baits her into chasing him into the house.
We put a battery powered doorbell on the door leading outside. My puppy Veronica quickly caught on but mostly rang it when excited rather than when she needed to go out.
But about six months ago it kicked in what it's for and she'll surprise us by going across the house to hit the bell and tell us she means business.
So it wasn't exactly accidental but took a year.
Also same as yours, "Go get your sister." She'll go try and figure out what her older sister is up to and bring her back.