Buy a Real Ice Cream Shake today, and get another one FREE on the spot, or receive a coupon for a FREE Shake on your next visit. I do believe they are also doing real ice cream sundae with one topping for $.99.

Here is the fine print found on the Sonic site
(Limited time only! Buy One, Get One Free Anytime offer ends June 27th, 2010. * Buy one shake at regular price (plus tax) and get one free shake of equal or lesser value now or receive a coupon for a free shake on a future visit. Coupon expires July 15, 2010. Includes Cream Pie shakes and malts where available.)

Thank you Fistful of Coupons