As you have to purchase products in order to get the freebie I did not post it in the freebie section.

OFFER TERMS & CONDITIONSFree* Retro T-shirt Terms & Conditions:
*To redeem your free Sugar Crisp, Shreddies, Honeycomb, or Alpha-Bits retro t-shirt enter the unique PIN Code found in specially marked boxes of POST Sugar Crisp 550g, POST Shreddies 725g, POST Honeycomb 525g, or POST Alpha-Bits 510g at Fully complete the order form and submit no later than 11:59 p.m. PT on February 29, 2012. Offer good while supplies of retro t-shirts last. Maximum of 20,000 Sugar Crisp, 40,000 Shreddies, 18,000 Honeycomb, and 12,000 Alpha-Bits retro t-shirts available. Selection of t-shirt sizes subject to availability. Youth sizes are not available in Quebec. Please allow 8-10 weeks for delivery. Limit of 1 t-shirt for each unique PIN. Please complete a separate order form for each unique PIN Code entered. Post Foods Canada Corp. reserves the right to decline your order form if your order cannot be filled. Offer open to Canadian residents only, 13 years of age or older. EACH UNIQUE PIN CODE CAN ONLY BE USED ONCE TO REQUEST A RETRO T-SHIRT.