Let's face it: Children, from toddlers on up to teens, are not well known for patience and forethought. Kids want what they want, and they want it now. It doesn't matter what it costs, or whether it's worth it. If you don't believe me, buy your teen an MP3 player from SanDisk (NASDAQ:SNDK) and send her to iPod High, where you either flaunt your Apple (NASDAQ:AAPL) or you take a lunch-room seat with the paste-eaters.

So what if I told you that every time the apple of your eye huffed and puffed or merely pouted, instead of costing you money, it might make you a few bucks? Sound impossible?

Not entirely. The world's biggest tantrum-tosser gives you this opportunity all the time. It's called the stock market. It's a place where all the brains and technology in the world can't overcome base and immature urges like peer pressure, childish greed, and mindless panic.

It's a place where great financial minds will encourage you to buy what's new and hip, no matter what the price. Shares of Research In Motion (NASDAQ:RIMM)? Go for it, dude! It's already richly valued, but so what? Everyone likes the Blackberry, right? Look at that top- and bottom-line growth! Never mind the lackluster returns on capital, or returns on equity that actually lag the average of the S&P 500. Oh, and pay no attention to minor potential competitors like palmOne (NASDAQ:PLMO), Dell (NASDAQ:DELL), and the rest of the computer industry.

And if you think the Street's youthful exuberance can cost you, wait until it pitches a fit. That's when analysts who are quite capable of determining a firm's real financial value ignore lead-pipe bargains and scream "Sell!" Why? To be cool like the rest of the kids.

There is another way: Invest like a grown-up.

It's a method followed by minor successes like John Neff, Warren Buffett, David Dremen, Bob Olstein, and others. And it's a path we follow at Motley Fool Inside Value.

It's pretty simple, really. It's refusing the urge to fall for the overpriced hot new item. It's looking for the quality firms that the fickle kiddies have tossed aside in their Streetish fits. It's buying Nokia (NYSE:NOK) late last summer, after it had been through some tough times, and seeing it rise from $12 to near $17 in only a few months. It's snapping up shares of Inside Value's inaugural pick, MCI (NASDAQ:MCIP), and seeing similar 40% returns.

Don't get me wrong; we don't expect quick bucks like these all the time -- and we all endure our share of sinkers -- but by controlling our immature urges and concentrating on what a company is really worth, we expect to see our current, market-beating returns continue for years to come. If you'd like to take a break from the Street's 24/7 kiddie cavalcade and learn how to invest like a grown-up, join us at Inside Value by taking a free 30-day trial. We're beating the S&P 500 by more than six points since inception.

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Seth Jayson is a recovering growthaholic. That's right, he's addicted to growthahol. At the time of publication, he had shares of SanDisk, but no position in any other firm mentioned. Dell and palmOne are Motley Fool Stock Advisor recommendations. View his stock holdings and Fool profilehere. Fool rules arehere.