Do you have a voucher code from Groupon or Living Social? Maybe you have a code from a flyer or email sale.
Great, to redeem your voucher and sign up for the event you like. Find the event you want to attend. Click on purchase a ticket like your going to buy a ticket to the event. This will take you to the shopping cart page where you put your voucher number in the “apply coupon” field and that zeros out your total due. Then you proceed with the checkout putting in your information but you will pay nothing, this adds you to the event list for that night.