PediaSure is offering a coupon in the mail for free drinks when you sign up for their PediaSure Rewards program.
Just fill out the form here with your personal info and child’s birthdate. The site says they also offer giveaways, so it might be good to check out if you have a young child.
The mailed coupons usually take several weeks to arrive, but I don’t see specific language on the sign-up page.