Booyah Breakdown: Mad Mysteries

That's because if you hold onto the stock too long in hopes that it will go higher, you'll often get burned. It'll tumble back down and your profits will vanish. So Cramer wants you to sell some or all of your position while you're still up so that you can cash in on at least some of your winnings.

How you sell that position is entirely up to you. If you're a "first-in/first-out" trader, you'd sell your initial investment first, then sell the next lot of purchased shares, and so on. Otherwise you can just pick which shares to sell. Just be sure to keep track for tax purposes.

Now, to be "long" a stock basically means you're just holding it in your portfolio. If you owned Microsoft (MSFT Quote), we could say you were "long Microsoft." You also believe the stock is going up, otherwise you probably wouldn't own it.

If you think the stock is going to take a dip and would like to try to profit from that fall, you could consider "shorting" it -- but remember, that's a risky strategy.

To sell a stock short, you must first borrow the shares of the stock you believe is going to tank from your broker.

So let's say you think Microsoft's Zune is going to bring the company crashing down. So you decide to short 1,000 shares of the company, currently trading at $29. You borrow the shares from your broker, sell them in the regular open market and now have $29,000 in your account.