If the friends in your social networks are suddenly singing an altruistic tune, you can place the blame squarely upon Walmart.

Or you might want to actually thank the corporate behemoth.

Maybe. Are you familiar with the excited plea, "Help Houston get to No. 1!" followed by a link? It's being flung far and wide across Twitter, Facebook, and everywhere online in between. And that's all Walmart's doing.

But why? And for what?

The big box behemoth has $1.5 million to award six lucky cities — $1 million to the top city and $100,000 to the five runners-up — in order to combat hunger in communities across the country.

The campaign, dubbed, "Fighting Hunger Together," asks you to like a corresponding page on Facebook. The metropolitan area garnering the most likes on Facebook scores a cool million for hunger relief. Easy enough, right?

In order to make this happen, Walmart pegged food banks nationwide as the community ambassadors for this campaign. Here in Houston, the Houston Food Bank is spearheading the efforts.

"Walmart is the largest food donor to the Houston Food Bank, and they're huge in terms of large-scale contributions," said Betsy Ballard, Houston Food Bank chief communications officer. "Walmart asked the Houston Food Bank to take the lead in bringing the money into the city. If Houston wins, we'll distribute the money among hunger relief providers."

Walmart couldn't have picked a better steward for the potential prize. The Houston Food Bank feeds over 137,000 hungry people each week, and distributed 65 million pounds of food last year alone.

And it looks like they'll be filling a lot more bellies in the near future, thanks to a generous $500,000 gift from the Houston Texans that'll fuel the opening of a 298,000-square foot distribution center in the spring.

The difference, however, is that the Texans didn't ask for anything in return for the half a million donation. Walmart, for double that amount, wants you to like a page on Facebook.

Is that worth it to you?

All that free advertising — far more than $1 million, mind you — for such a teeny tiny price tag (relatively speaking). It certainly sounds like Walmart's getting a great deal — coming off as the hero, without spending much money at all. There's much, much more where that came from, but the vague whiff of exploitation is unavoidable when it comes to the value to the recipient.

"It's an ingenious campaign on their part. Who can't see it as an ingenious way to generate grassroots interest?" Ballard said. "Walmart has a long history of supporting hunger, and Walmart will be there for the hunger relief community. They don't have to help us, but they understand hunger relief is an essential human need."

But you'd like to think a corporation as profitable as Walmart would see hunger relief as more of an obligation than a clever marketing campaign. In a perfect world anyway.

One can't help but wonder why Walmart can't simply give the money away, like the Texans did, in true charitable fashion. Why must Houstonians wanting to help hunger have to do anything for the money? Since when is philanthropy about giving to get back?

But there's no denying that, if Houston wins, it's $1 million our city didn't have — and the Houston Food Bank's track record guarantees that the money will be effectively spent on making sure less and less Houstonians go hungry.

The contest ends Dec. 31, so you don't have much time left to help — or to get your social networks in on the contest. Houston currently sits in eighth place out of a 100 cities, one spot behind Dallas. Fresno, Calif. — a city of less than 500,000 people — is in first place.

So go ahead. Click the Like button already. No matter how you feel about the campaign.