Chat Pins?

Could someone explain to me how to do the scam where you go on a chat room and get a free pin?

 

please use the search button before asking this

 

Tell someone your a hot girl send some pics, then tell him to send a text to the runescape pin service for a free pic ( just tell him its your number )

Then you say what were the numbers after he says wtf.

he gives you and you leavechat or w/e