Dan Snyder‘s pushing-up-daisies-ish theme park chain, Six Flags, finally got the warning from Wall Street that we all knew it would: Shape up or get out.

And there ain’t a whole lot of shaping up going on up there lately.

The New York Stock Exchange put Six Flags, which is carrying more than $2.3 billion in debt, on notice that its stock was on the verge of being delisted. Warnings like this are issued when a firm’s shares close at an average of less than a buck a share for 30 consecutive days.

Absent a fiscal miracle, Snyder’s simplest option to fight the delisting would be to engineer a so-called “reverse-split,” in which every two shares of Six Flags stock (SIX) would be consolidated into one, theoretically doubling its value.

But things have gotten so bad at Six Flags recently that even that strategy might not be enough to keep Snyder trading with the big boys.

Six Flags was selling for $11.93 a share shortly after Snyder’s 2005 takeover of the company, but has been diving like Greg Louganis ever since.

Earlier today, the stock could be had for 40 cents. Double that, and you’re at 80 cents — or still well below Wall Street’s Mendoza Line of a buck a share.

Bill Gates is among those to be dealt the beating of a lifetime under Snyder. Gates’ money company, Cascade Investment, L.L.C., owned a reported 10,210,600 shares when Snyder grabbed the reins of Six Flags.

So in March of 2006, Gates’ investment was worth $121,812,458.

As of this morning, Gates’ grubstake was good for just $4,084,240.

That means Gates is down at least $117,728,218.

Guess the cure for malaria and the eradication of global poverty are gonna have to wait.

Good news for Gates: He’s a PC. Macs are a little extravagant for a guy who’s taken a nine-figure hit.

Good news for Snyder: There’s always Chapter 11! (Around here, bankruptcy “isn’t bad news.”)

Keep the dial right here for all the breaking news in Snyder’s Six Flags soap opera.