Saw this in my kids happy meal promoting the new Lego Batman movie.
Legoland - Kids Go Free with Paid Adult (Valid through 11/30/2017)
Buy tickets in advance to Legoland Resorts or Legoland Discovery Centers!
and enter Promo Code 179902
There was also a coupon for "Free Kids ticket with Purchase of General Admission Ticket" (kids under 48") for Six Flags but its a coupon that needed to be presented. Expires September 17 2017.