I googled "naked giant stuffed duck" and came across the following site:
http://www.happynursery.com/melissa_doug_giant_plush.htmIf you scroll down they have Mr. DUCKIE and The Giraffe that House was "fighting" when he was in Rachel's nursery.
I don't know anything about the store, but I figured, if someone here has a child, you can use your child as an excuse to buy a giant duck. :-)