Black Friday is the shopping day of the year here in the US where companies go from "being in the red" meaning that they are losing money to "being in the black". Typically retailers discount heavily, especially on consumer electronics, in a hope that in the post-Thanksgiving haze of stuffed tummies and dulled brains, that we pour the contents of our wallets out onto their counters in exchange for goods.
As Mr. Spanky is always on the prowl for the interesting and amusing, he came across this "coupon" that celebrates Black Friday.
The talented illustrator here is poking fun at our rampant materialism and reminds us that this obsession can never be satisfied and in the end becomes your owner. The picture of the cow is in reference to the golden calf created and then worshipped by the Israelites while Moses was up on the mountain getting the ten commandments from God (Exo 32:1).
It made the Spankster snort with suppressed laughter, much to his embarrassment, while riding the train home.