Investment guru Jim Cramer is urging savvy investors to resist the temptation to jump aboard what he sees as Wall Street’s latest fad:  anything and everything to do with marijuana, cannabis and pot.

Investors are craving marijuana stocks as Canada prepares to legalize pot next month, leading to giant gains for Canada-based companies listed on U.S. exchanges.

Billions of dollars have poured into the stocks in the last few months, and investors smell green (money, not leaves) in the air as they consider the opportunities these companies might have as the marijuana market in Canada grows, along with the possibility that the U.S. and other countries could follow suit.

However, the "Mad Money" host said said next month will instead be a "sobering moment" for pot stocks.

"October 17 is not going to produce the 'high' so to speak that people think," Cramer told CNBC. "I don't want people to get hurt."

Cramer has said there's nothing in terms of company fundamentals or industry trends to justify the dizzying moves in pot stocks this week, CNBC explained.

To be sure, the Associated Press agreed with Cramer, reporting that some experts are concerned that the ending of Wall Street's recent refer madness will be a buzzkill.

The value of one company, British Columbia-based Tilray, has jumped tenfold since its initial public offering just two months ago. The company had $20 million in sales in 2017, but it's now worth considerably more than Macy's or Hasbro. With those huge gains have come extreme swings.

Wednesday was a trip for Tilray stock (TLRY): after closing at $154 the previous day, it opened at $233 a share, soared to $300, and then plunged to $151 before rallying to close at $214. Trading was halted several times because of that volatility.

For some people on Wall Street, it's bringing back unpleasant memories.

"We just went through this eight months ago with cryptocurrencies," says investor Ken Mahoney, CEO of New York based Mahoney Asset Management. He said the investors buying these stocks at their current prices are already betting on enormous successes, but even if legal marijuana takes off, some of the companies will fail.