Refers to merchandise that you pick up for someone else while shopping for your own items, either because this other person is unable to travel to the store himself, or because he is not a paid member of the big-box outfit where his desired items are offered, and so he has asked you as a member to obtain the items for him at the warehouse's bulk-package discount.
I don't buy enough household consumables to justify the $89-per-year membership-fee that Sam's Club charges, so I just piggyback-purchase them through the large family down the street.
by QuacksO July 23, 2018