1. A computer-implemented method for providing a merchant with data for verifying an identity of a consumer that has tendered a payment card to purchase a good or service from a merchant during a first transaction, the method being performed by an intermediate computer in communication through respective networks with a point of sale (POS) device of the merchant and a computer hosting an online social networking site, the method comprising: receiving a request by the POS device for data to be used to verify an identity of the consumer; accessing or receiving data of an account the consumer has with the online social networking site; determining a challenge question and response options based at least in part upon the account data, the response options comprising a valid response that is a content item of the account and at least one invalid response; and transmitting the challenge question and the response options to the POS device for presentation to the consumer through the POS device to allow the consumer to select a response option to answer the challenge question and allow the merchant to verify the identify the consumer before the first transaction has been completed based at least in part upon whether the consumer selects the valid response.