Personally, if I were to go to Canada and purchase their OTC codiene products, I would probably just pay the little bit extra and mail them to myself from Canada (Actually, I have done this with boxes of Cuban cigars). You are scrutinized much, much more crossing back to the US (because of terrorism events) than a mailed package ever will be.
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Misty morning, clouds in the sky
Without warning, the wizard walks by
Casting his shadow, weaving his spell
Funny clothes, tinkling bell