The girl, known only as 'Bex' on Twitter, shared her genius with her 15,400 followers on Twitter.
The post is a screenshot of a text message exchange with the comment: "Changed 'no' in my mom's phone to 'HELL YEAH' hahahahahahahahhaha."
The message from Bex to her mum reads: "Can i have some people over the drink a little?"
Mum, clearly not keen, tries to reply in the negative, but thanks to Bex's trickery, laughter abounds with: "Umm HELL YEAH??"
The Tweet has gone viral, with more than 5,220 retweets.
Be careful, parents - there are more tricks to this technology than you can possibly grasp.