My friend got a pay day loan?

and used me as a reference NOT a co signer! the payday loan company calls and leaves me a voicemail saying they are suing my friend and my name will be included in the lawsuit..I am not sure how they got my social security, and the bill collector said I was a reference not a co signer. I need to appear on court Feb 4. I have not received a letter and this is my first phone call