I've posted in the past about Costco coupons, and how they track and combat people trying to skirt the limits that they impose on their monthly coupons. Many products have a quantity limit, usually the better the deal, the lower the limit you can buy at the discounted price.
One thing I've found is that there's a completely legal way to get around this policy and take advantage of the savings: Call on your friends and family for help.
Since Costco tracks purchases on your account, you can't simply exchange coupons. Instead, if you want extra coupon savings, you have to call on those you know to purchase items for you, then collect the items and pay them back.
This assumes, of course, that the person you're exchanging with would have no need for the coupons themselves, and there's always the matter of having to go through the hassle of exchanging the product and the money, but sometimes the deals are so good, it's worth it.
And the best part is that Costco can't punish you for exceeding your coupon limit, because they never know!
My parents drink Taster's Choice instant coffee. We never do, so whenever the coupon comes around, we usually purchase it for them and then exchange the money and coffee when we see them (which is regularly).
We've also done this exchange with my parents getting stuff for us, as well as a recipricol exchange with our in-laws. In the end, this has helped us all save a great deal of money.
Many products have such a high limit that this doesn't come into play, but on those items where the limit is one or two, and you can benefit from saving more, doing such an exchange can be a very saving savvy move.