You could be sued for the remaining amount due under the lease agreement--that is, after giving effect to whatever payments were made, for whatever is left under to be paid for  the full balance of the lease term. As a co-signer, you are legally liable for the debt; the furniture store and/or its collections agency may go after any of the signers or co-signers they choose to recover the money due them. They could also recover the furniture, since once you are in default on a lease, you are not allowed to keep the leased property. If you refuse to return the leased furnture, you could be sued for its value as well, and also potentially be charged with theft, since you would know be taking property to which you have no right.