Extend the Story - Add a Room

You are sitting on your bed in yours and Lily's bedroom, trying to read while your annoying twin sister keeps on bothering you.
"Hm... right," you mumble as she continues pestering you, finally shouting, "COULD YOU PLEASE LEAVE ME ALONE?"
"No!" Lily-Rose replies, giggling.
You open your mouth to yell at her, but are stopped by a tapping on your window.
What do you want to do?

Get up and see what is actually making that noise