Sorry, folks. When I mentioned a four-bagger in the headline, I literally meant four bags of rice. That's all you're currently allowed to buy at Wal-Mart's (NYSE: WMT) Sam's Club. Costco (Nasdaq: COST) is mulling a similar measure.

These are tough times, I know, but a run on rice is not what I expected.

News agencies are starting to talk about food shortages, and rice is a big focus of the problem in many countries right now. As is always the case with supply and demand, the price of the grain is going up. The Los Angeles Times, meanwhile, reports that Costco is not only considering a limit on rice purchases but has also seen sales spike on flour and some cooking oils, and it's thinking about limiting purchases on those items in specific stores.

The problem is not quite as dire as it sounds, even if it does carry global implications. Many small businesses that shop at warehouse stores such as Sam's Club and Costco have apparently been buying bags upon bags of rice in hopes of hedging against the looming threat of higher prices.

The bags being rationed are the big 20-pounders, so it doesn't appear that we'll be unable to get our small boxes of Uncle Ben's anytime soon. And you don't need to start wondering how hard it would be to start up a backyard rice paddy.

But the situation does draw our attention to the high commodity prices that many companies are struggling with these days. Starbucks (Nasdaq: SBUX), Panera (Nasdaq: PNRA), Tyson (NYSE: TSN), and Kellogg (NYSE: K) are just a few of the companies that have disclosed the margin pains of rising commodity costs over recent months. Prices for corn, wheat, and soybeans have blasted off in recent history.

High prices for food and energy are pinching consumers -- and, it appears, driving them to discounters and bulk warehouse companies. No, it's not time to hole up in the bomb shelter and clutch your hoarded Rice Krispies treats, but there's still no way to sugarcoat it: These are indeed difficult times.

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