The mission is important and I take it very seriously.

In my hands I’m clutching three cans of cat food, a carton of half ‘n half, a bag of chopped walnuts and a jar of peanut butter. If I’m not in my car and headed for home in three minutes or less, I’ll consider this mission a failure. I have important things to do, you know. Important things involving cat food and chopped walnuts, apparently, but just you mind your beeswax.

I begin scouting the checkout lines – one doesn’t simply commit himself to a line, one scans them all. Studies them. Assesses them the way a good angler will assess a variety of fishing spots before dropping anchor.

I’m not looking at the length of the lines as much as I’m looking at the people within them. Are they pushing carts or carrying baskets? Do they have their wallets and purses at the ready, or are they yacking on their phones with seemingly no idea that at some point, they will be asked to pay for their goods?

Some folks you can just tell are going to be trouble. They have a stack of coupons three feet high and they’re watching the cashier with narrow eyes, the way a gunslinger watches his opponent 25 paces away. If the total is one cent higher than they calculated, there’s going to be trouble – line-stalling trouble of the kind that can completely derail a smart shopper’s mission to get in and out as quickly as possible.

I also look for people who might be ardent smokers so that I can avoid them. A man or woman who appears to be breezing through the checkout can nonetheless throw a wrench into the works if he or she asks for a pack of smokes, or worse, a bag of tobacco and rolling tubes.

The clerk, a cherub-faced youngster, will have to call for a manager who is old enough to sell tobacco products. The manager will come over, but will have forgotten the key to the cigarette case. He or she will then grab the wrong item (it’s almost always a menthol thing) which will tack another crucial 30 seconds onto the progress of the line.

Smoking kills, brother. Steer clear of smokers in the checkout line.

One also considers the cashier, be it man or woman, young or old. Gender and age will tell you nothing about the speed and agility of the checkout clerk. I’ve encountered teenagers who move with the syrupy speed of the dying and my mission was obliterated because of it. I’ve come across clerks pushing a hundred years old who nonetheless rang up my goods with such blazing speed that my walnuts actually roasted in the bag. True story.

You want to find the clerk that has his or her own mission. He or she might make small talk, sure, but while doing so, those cans of creamed corn, bags of Fritos and jars of olives are flying across the scanner and into bags. That clerk pretends to like you – did you find everything you were looking for today? – but brother, he or she just wants you gone as fast as possible. And who can blame him or her?

That’s the clerk you want; a clerk who’s going to challenge you to swipe your card a little faster and respond to the prompts with a little more haste. (While we’re on the subject, why does Shaw’s insist on having those superfluous prompts at the end of the transaction. “Is this amount right?” Press the green button. “Are you sure?” Press the button again. “Have you really thought about this amount and what it means for you and your family?”)

So, in the market on Monday, I found that there were several people like me who were hell-bent on finding the speediest line. Most were men, but there were a few women in the mix. We jockeyed for position, choosing one line only to hastily frog-hop into another one before anyone else could beat us there. We eyeballed idle clerks to see if they might open a new line (which always leaves a well-mannered shopper with a conundrum: do I scramble over to the new line like the greedy rascal that I am, or does the cranky old man behind me deserve it more?) We feigned indifference about our checkout experience when in fact, we were approaching the endeavor with the life-or-death intensity of battlefield generals.

One fellow was particularly good at it, to the point where he was challenging my status as fastest checker-outer. When I moved into a new line, he jumped into my old spot, making me question whether I’d made the right move. When he chose a different line, I jumped back into the original line, at a loss because a woman with a gallon of ice cream under each arm had swooped in with the speed and stealth of an auk.

This went on for a minute and a half before my rival shopper approached me, sweaty and red from the checkout line calisthenics we’d been engaged in.

“You really ought to write something,” he said, “about the art of picking the right checkout line.”

“I’m sure I don’t know WHAT you’re talking about,” I said.

When he wasn’t looking, I peeled the bar code sticker off his banana bread. Enjoy that price check, rookie. This town ain’t big enough for the both of us.