You must have a thick skin to get good cardboard. If you think shopping for fabric is hard, you haven't tried cardboard hunting. You must not bat an eyelid when people stare at you trying to load good cardboard into your vehicle. You must have nerves of steel when driving home when all you see in the rearview mirror is brown. You should probably always carry a pocketknife with you, because you never know when a delicious cardboard box will appear and need to be flattened in order to be taken to its new home. If you eschew weapons, you must always have at least one long fingernail in order to peel off the packing tape and turn 3D into flat. Your children must be pre-conditioned so they sing, "We're so lucky! We're getting cardboard! Look! Mum's making a tent in the car!" when said Mum is internally struggling over whether to take just one of the two boxes sitting in the recycling bin, or both.
Where did I find today's free cardboard gem, you want to know? IKEA, of course, where everything is flat-packed to keep costs low and let you easily take stuff home. Think they were referring to their furniture? Hah! Think again.
P.S. I was kind enough to leave the other box, you know. Not too late to get in your car now and snag it.