Smartphones are wonderful things. They made cool things like the tel: link useful, allowing us to call numbers directly from websites and emails.
Handset USSD codes are wonderful things. They allow direct comms between service providers and handsets to do stuff like checking account balances, show the handset IMEI or even factory reset the phone!
Of course, the internet being the internet, someone has found out the shortcode to factory reset the Samsung Galaxy S3. This is predictably being pushed around the internet by the virtue of telephone links embedded in hidden frames.
The USSD code to factory data reset a Galaxy S3 is *2767*3855# can be triggered from browser like this: <frame src="tel:*2767*3855%23" />