Watch the latest video at FoxNews.com Ever wonder if there's a way to gauge whether this stock market's getting ahead of itself? Well, there's an app for that. And if your company's name so happens to be WhatsApp, a lot of money in that. Try 19 billion bucks! That's how much Facebook is paying for WhatsApp, a little known mobile-messaging service. 19 billion dollars? Now I know why the 23-year-old founder of SnapChat didn't snap at the $3 billion Facebook was offering for his company last fall. He figured he'd roll the dice and wait for a better deal. Sound crazy? Maybe not. But if all this doesn't sound a bit frothy to you, it does to me. Because maybe it is just me, but I think I've seen this game before. The last new paradigm: Where it wasn't the dimes companies were making, but the promises they were offering that really mattered. Remember all those companies that achieved sky-high valuations based not on their profits, so much as their potential? There's nothing wrong with investing on a hunch, but if I'm Facebook and I'm plunking down 19 billion bucks for a company that hasn't even been around two years, I sure as heck hope I'm going on more than a hunch. Then again, I'm Facebook, right? And come to think of it, I'm worth tens of billions myself based on kind of the same hunch, that the great social Web is more about users than dollars, so buy the users and, eventually, you'll be grabbing the dollars. Look, for all I know these companies might be worth all the dollars and all headlines they're attracting. Maybe they are this decade's Amazon or Google. Then again, maybe some are less like eBay and more like eToys. Remember them? Big IPO. Big category killer. Before management spent itself into a big old black hole and ends up getting bought out by your standard category toy store. That's the thing about dot-coms -- many more turn out to be dot-bombs. Because for every new digital darling, I regret to say there are ten times as many dogs. Literally. Pets.com ring a bell? All I'm saying is beware companies whose CEOs only recently started shaving. You might end up being the one getting nicked.