Another thing to keep in mind, and this may apply for others - those that have the cards but did *not* sign the membership agreement: the wife and I both have COSTCO cards...business memberships...provided by the boss (family business)...the boss may have signed the membership agreement, however...neither myself nor my wife have signed any such agreements. FWIW.
I think the "You bumped into my insulin pump...." reaction is the best out there...or maybe the colostomy bag...
