Update: I thought its only me, but it seems like others are having trouble printing the coupon online (it links to a Babies R Us coupon instead). Therefore, we recommend either getting a flyer from their stores or showing the bugged coupon to the cashier.
This week from August 26 to September 1, Toys R Us United States will be offering $10 off $50 LEGO Purchases. For instore purchases, they have a slightly better deal where you get $15 off instead of $10. (just make sure to use the coupon in the flyer)