K-mart was a store that wal-mart essentially ran out of business because they sold the same type of stuff, but managed to do it cheaper.
Back in like the 70's and 80's the store would have a blue flashing light on a rolling cart that the6 would park in an isle where the "blue light special" sale was. It was a goofy thing.
They also had a thing called "lay-a-way" where you picked out stuff to buy but couldn't pay for. They'd bag up all your stuff and keep it stored away in a room while you came in and made payments on it until it was all paid for, then they'd give you your stuff. Strange times.
For those who weren't around back then, K-Marts literally had a blue rotating light (like what you would imagine on top of a really old police car) up on a rolling cart, and it would get parked in an isle to mark where "the blue light special" sale was.
One of the most bizarre feelings is when things that used to be commonplace are explained to the youts like museum pieces.
"Now, this is what we used to call a ditto machine. It used chemicals to make good smelling purple copies of things!"
"These metal rods were called 'rabbit ears'. You needed to position them juuuust right to watch a live broadcast!"
"It was common for people to have a small circular scar, usually somewhere on their arm, from a smallpox inoculation. But if the scar had a spiral pattern, it came from a playing around with a car cigarette lighter!"
Sears: think Walmart but without a grocery section LONG before Walmart. Used to be catalogue only. Big box warehouse basically
K-Mart is cheap, shitty Target, basically. Always felt that way to me, anyway.
So the joke is that most normal babies come in a kit from the Sears catalogue (or box store) but Calvin was a cheap, Store-Brand deal that's almost as good for half the price!
Explain like I'm Calvin is a community like Explain Like I'm Five. Only instead of providing a simple easy to understand explanation, it's explained in a silly nonsensical (and incorrect) way. Much like how Calvin's dad often explains things to Calvin.
Well, it'd be great fun for you and your (sometimes imaginary) friends, but it'd make you an awful parent that completely sells off the trust relationship with your child for a few giggles. Ask me how I know. Don't take Calvin and Hobbes as actual parenting advice.