Okay, let me tell you what happened-

So Simon and Rose pretended to ignore Poppy for a prank, but Rose also pretended to hate Poppy as a prank-

And due to that, Poppy thought Rose actually hated her, and Simon found out about what happened afterwards-

Simon: Rose, what did you do?!
Rose: The prank we were doing.
Simon: I never said to pretend to hate her! #remix