We all buy stuff on impulse occasionally. We go into the store for milk, bread, and 2-for-1 extra cheese pizza, and we come out with a windshield defogging cloth ($3.99), a package of four brown magic markers that "instantly hide scuffs on your precious wood furniture" ($5.29), and the latest Oprah magazine. (Oh, all right, and People, too.).

For just a moment, everything is right in the world. Then we get home, after streaking the windshield with the useless greasy cloth, and soberly tuck away in the junk drawer our impulsive little divertissements.

Not me. My impulse purchases don't fit in the junk drawer. Mine are big. Huge, in fact. I super-size my shopping mistakes. I could give big spender Britney Spears (the pre-reformed Britney, that is) a real workout at the mall.

So you think you can shop? Ha!
My most recent impulse purchase? A couch: 90 inches of sleek, mid-century modern seating in its original nubby fabric (light wear). By my calculations, eight albatrosses of average girth could sit comfortably on it -- though they, like the dog, are banned, lest their toenails snag the upholstery.

You might be thinking this column is merely a 1,000-word advertisement to sell my couch, to which I reply, "Is it that obvious?" and add: "Interested buyers can reach me via email."

Since the Fool editors do actually read this stuff before it's posted, I've thrown in a few tips on dealing with similar bouts of shopping stupidity. (If you prefer to skip the play-by-play, scroll down to the end of the article.)

The couch is mine! The couch is mine!
Back to the couch. I saw The Couch on a lazy Sunday at the flea market. Other discerning shoppers quickly started hovering, but I staked out my territory -- which is to say I sat on the sofa -- to make it clear that it was mine. Plus, I was the first person to make eye contact with the dealer.

The transaction went down quickly, thanks mostly to my shopping pal Pam -- a complicit style maven, quick with affirmations and willing, with checkbook, to lend me the extra dough that was above my daily ATM withdrawal limit.

Fellow shopaholics can identify with my glee -- the euphoric "buyer's high." Author Sophie Kinsella dissects our affliction in Confessions of a Shopaholic, which follows a fictional financial writer's shopping addiction and her schemes to pay back her debts. She spends 310 pages dodging lenders and patching her sorrows with swirly new coats, pointy-toed boots, cashmere sweater sets, and monogrammed luggage.

What an amateur. A few new coats? Feh. I bought a major piece of statement furniture with half as much introspection.

Why we buy, and one big upholstered regret
Retailers thrive on our kind. In Influence: Science and Practice, Arizona State University psychology professor Robert Cialdini examines the science of selling and counsels marketers on "triggers" that make us buy strawberries in bulk and dreadful sweaters that we never wear. In other words, he explains how retailers get us to overspend.

Scarcity, demand, and the momentum of the shopping experience were on their side that fateful couch-purchasing day. So, too, it seems was the deceptive outdoor lighting. When the sofa was delivered to my home later that afternoon, the buyer's high came to a screeching halt.

There it was, being lugged into my living room. My couch. My green couch. Wait ... green?! OK, not green green, but a pale celadon. This couch was not green at the flea market. This couch looked off-white. Maybe a little dirty, but definitely off-white.

Green, dear readers, was not an acceptable color in my decor scheme.

From identification to acquisition, my couch-buying high lasted exactly 52 minutes and 34 seconds. Let me do the math for you: At $650, that's $12.41 per minute of glee.

7 lessons from a shopaholic
The lessons learned from the experience, however, are priceless. So in the spirit of generosity (and to butter up any potential used-couch buyers), allow me to share them with you:

  • Consider the opportunity cost of your purchase. Calculate what that money would amount to if you invested it for the long term or even socked away half of it to save for a bigger treat in the near future.
  • Leave the credit cards, debit cards, cash, and checkbook at home. Time has a way of curing a bad case of "the wants."
  • Just because it's on sale, that doesn't mean it's a bargain. Ask yourself whether you would buy the item at full price. In fact, double the price of the object of your desire, and ask yourself whether you'd pay that much to call it yours. This may seem unrealistic, but it will give you a good idea of how much you value the object.
  • Deal with your mistake immediately. Don't dwell on it. Return it. Sell it. Donate it. Just get rid of it.
  • Don't make a big mistake bigger. They call this "throwing good money after bad." Trust me, or else you'll spend weeks shopping for the perfect shade of green throw pillows, accent rugs, and shoes, or throw away a grand on reupholstering costs.
  • Write about your boneheaded purchase in the most public forum available to you. The shame and angry email about your shallowness will keep you from making any major purchases for at least 12 days.
  • And finally, just don't buy it. And by that, I really mean don't bring my friend Pam with you to the flea market.

Still got the urge to splurge? Let Dayana intervene: