Head on over and get a free voucher valid for a FREE medium Cherry Limeade with any food purchase at Sonic. You will just need to click the blue Get Offer button and it will be saved for you.
To print your voucher, click on My Offers. Your voucher will be shown and you can click the print button so you can print and take it with you (make sure you mention the coupon when ordering).
This coupon is valid at participating locations, so make sure you ask before you try to redeem it. The voucher is valid through October 31, 2013.