The woman was fed up with waiting in line while Geroux racked up savings using her coupons. A pair of airborne sneakers and a few expletives later and the potential battle had been defused and Geroux walked away with her purchases and savings in tact.
"I've got a pretty thick skin, nothing really fazes me," she said.
The world of "extreme couponing," as participants call it, is a no-holds-barred pursuit of savings that has earned itself a weekly TV series and countless obsessive Internet followers who strive to maximize their savings at the checkout by spotting the best sales and by hoarding coupons.
Entering the world of extreme couponing was almost a last resort for Geroux, but over the past three years it has become a lifestyle. It began when the Hamilton, Ont., resident moved to Toronto and got a big reality check when her monthly rent was far higher than she expected and daycare costs soared past her budget.
She had to start saving fast.
"I was extreme from the first time I shopped," said Geroux, who runs a blog called Extreme Couponing Mom, an extensive database of the latest discounts.
"I walked into the store and got $300 of stuff for like 20 bucks."
For the average Canadian, walking into a store with a binder of clippings and a clearcut strategy isn't practical, but diehards say there are several tactics that can be incorporated into anyone's shopping list.
Price matching is one of the easiest ways to reduce grocery bills, and fellow saver Kristine Oberg says it's the basis for how she slashes expenses at the supermarket. Every weekend she scans local flyers to highlight items that are on sale at other retailers.
"You take the flyer from that store, bring it to your local store and get the same item for the (lower) price," she said.
A price match is quick and easy because the cashier will use the flyer as a reference to generate a discount on the spot.
One of the best kept secrets of the retail industry is the Scanning Code of Practice, a voluntary standard used by most major retailers in Canada. The goal is to ensure consumers are paying the correct price at the checkout, and if they aren paying more than the stickered price, the item is free to a maximum of $10.
It's surprising how often food products are priced wrong on shelves. When Oberg went shopping last week she noticed that all but one kind of Quaker instant oatmeal was on sale. She carried the cinnamon-flavoured box to a price scanner to confirm her suspicions.
The Quaker box was on sale, but wasn't marked properly. So, Oberg took a picture of the price on her phone, paid for the item at the cash, and notified the customer service desk.
She was issued a full refund for the oatmeal, saving more than $3.
On a lucky day, shoppers can save even more on mispriced items, said Geroux.
"I could walk out of there with 10 or 15 free bottles of shampoo and conditioner because they didn't price it correctly," she said.
"A lot of people are so busy ... they aren't paying attention at the register. I turn that little display right towards me so I can watch the scanner."
Internet coupons are also finally gaining more acceptance in Canada. This year, both Metro (TSX:MRU) and Food Basics changed their policies to include coupons printed from computers.
Geroux also recommends stocking up when there's a big sale, which is one of the most popular habits of frugal shoppers. To maximize those savings even further, hold off on using coupons until the items are marked down, which for many products happens once a month.
If you prefer to operate in stealth, a few smartphone apps are available in Canada that don't require you to carry physical coupons. Checkout 51 (available for Apple's iPhone and Android devices) lets shoppers submit a photo of their weekly supermarket receipt and receive cash credits that will be paid out through personalized cheques.
"It's good for people who don't want to be embarrassed by coupons," said Geroux.
While saving all of this extra money certainly helps your pocketbook, it's important to create a plan for what you'll do with the cash, said Sue Neal, regional director of Investors Group.
She recommends placing the money in a fund.
"Now you can really see the savings you're making," Neal said. "It could actually get you more excited about using the coupons."
Geroux chooses to spend the money she saves on other items.
"I'm not cheap — I have Coach bags, and I like nice things," she said.
"But I would rather have money to buy my kids Nike shoes and name brands, rather than spending all the money I earn on things that are either flushed down the toilet or in our bellies."
Vacations are more Oberg's style, and she's using the money she's saved to fly to Los Angeles this fall with her husband where they will attend a role-playing video game conference.
"I'm lucky that I don't ever have to worry about going into debt to do what I need to do," she said.
"I think that's one of the valuable things that couponing and price matching has taught me."
Extreme Couponing Momhttp://extremecouponingmom.ca/
Kristine Oberg's Frugal Kris bloghttp://www.frugalkris.blogspot.ca
Couponing in Canadahttp://couponingincanada.ca