Bond guru Bill Gross is pulling a Flavor Flav. He's telling people to not believe the Trump hype.

Gross, formerly one of the top dogs at fixed income powerhouse PIMCO and now a fund manager with Janus, wrote in his most recent monthly outlook that investors are too excited about Trump. He thinks Trump's economic promises are too grand.

"Don't be allured by the Trump mirage of 3-4% growth and the magical benefits of tax cuts and deregulation," Gross wrote.

"The U.S. and indeed the global economy is walking a fine line due to increasing leverage and the potential for too high (or too low) interest rates to wreak havoc on an increasingly stressed financial system," he added.

Wall Street hopes Trump's plans to roll back Obama-era rules on banks and health care and reduce taxes for the middle class and businesses can push the economy into a higher gear like it was during the Clinton and Reagan administrations.

But Gross is worried about the amount of credit outstanding in the U.S. -- as well as in China. He made several comparisons to 2008 when the collapse of Lehman Brothers sent the entire global market into a tailspin.

"Our highly levered financial system is like a truckload of nitro glycerin on a bumpy road," Gross wrote.

"One mistake can set off a credit implosion where holders of stocks, high yield bonds, and yes, subprime mortgages all rush to the bank to claim its one and only dollar in the vault," he added.

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Gross is worth listening to, but it's also worth noting that he's been sounding alarm bells for some time now.

And this is not his first criticism of Trump. In December, Gross warned that "investors must consider the negatives of Trump's anti-globalization ideas which may restrict trade and negatively affect corporate profits."

What's more, Gross' track record also hasn't been as good as it used to be.

So some might argue that his complaints are sort of like the famous boy who cried wolf.

Brian Nick, chief investment strategist at TIAA Investments, said he agrees with Gross that the stock market may be too excited about Trump, while bond investors are showing a little more trepidation about the possibility of higher interest rates.

Nick said that the bond market is acting like the sober designated driver while the stock market is closer to euphoria.

But he's not predicting another Lehman-like collapse. Instead, Nick thinks that the market may just cool off a bit and flatline until there is more evidence that Trump will get what he wants from Congress.

"Valuations are high right now and I'm not sure how much higher they can get," Nick said. "The market is pricing in too much optimism about the speed of infrastructure spending and a fiscal boost from tax reform. It's close to a best case scenario."

Melissa Brown, managing director of applied research at Axioma, added that she's surprised that volatility is this low given some of the risks that still remain.

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Wall Street's so-called fear gauge, the VIX (VIX), is down nearly 15% this year and hovering near multi-year low levels.

And CNNMoney's Fear & Greed Index, which looks at the ViX and six other indicators of sentiment, has been showing signs of Greed or Extreme Greed for most of this year.

That could be a problem, particularly because Gross fears that the Federal Reserve and other central banks around the world won't be able to respond to a new crisis as adeptly as they did eight years ago because they are out of ammo.

Most have already slashed short-term rates and launched so-called quantitative easing programs -- buying long-term bonds to keep their yields low and spur more borrowing.

"Today, central bank flexibility is not what it was back then," Gross said.

He did praise Fed chief Janet Yellen, saying that she has been like a modern-day Goldilocks who has kept bond yields neither too high nor too low.

But he added that mounting debt loads have the potential "to wreak havoc on an increasingly stressed financial system."