She's intentionally malicious because you're a tightass.
Let her do what she wants.
Yeah you were put in charge, stop being a tightass.
And no, installing a game is as easy as "You can use the computer as long as you don't close this window or do anything to it, deal?"
Oh be quiet. He is doing what his parents want him to. Besides, if she was caught on the computer when their parents got home he'd be in as much trouble as her.
