Andrea was moving up the line and everything seemed fine. Until a snobby (yet attractive) woman threw an insult at her, calling her a cow, among other things. Andrea was so infuriated that she yelled out "I wish you were a cow, you pompous stuck-up bitch!" This was her second wish, so it was granted to the person who was mocking her, as if she had spoken it.
The words "I wish" were what grabbed Jon's attention, making her look in that direction. And shortly after, she witnessed the woman who spoke them transform into a cow. A real cow. The woman who was throwing insults panicked, as did all the people who heard the wish. All of the commotion excited the cow, which suddenly ran further into the store, trampling both shoppers and merchandise.
"Oh, shit," Jon muttered, running towards the mayhem. But the situation was way out of hand, there was nothing she could do. Except, she could use the stone, to at least maintain some order.
"I wish ..."