Boxer Floyd Mayweather just promoted his third ICO for a crypto called Centra:

Centra's (CTR) ICO starts in a few hours. Get yours before they sell out, I got mine

— Floyd Mayweather (@FloydMayweather) September 18, 2017

Spending bitcoins ethereum and other types of cryptocurrency in Beverly Hill

— Floyd Mayweather (@FloydMayweather) September 15, 2017

The initial coin offering (ICO) craze seems to have only grown larger. With ICOs earning a combined total of more than $1.8 billion in fundraising proceeds for a wide variety of ventures and start-ups, it was only a matter of time before the trend began to have a wider impact. (See also: Blockchain ICO Offerings Have Outpaced VC Funding This Year.)

There has been concern that the ICO phenomenon might open the door to potential hucksters, particularly as a number of companies used their funds raised to immediately cash out of the game and secure fiat currency. And in a move that shocked the wider cryptocurrency world, China's government recently announced plans to block all ICOs from its markets. (See more: China Halts All Cryptocurrency Exchanges to Curb 'Risks'.)

Still, there are those looking to cash in on the opportunity anew. Many of the newest ICOs have come to be associated with celebrities. Here's a look at the rise of the celebrity ICO and what its broader implications are.

Mayweather, Hilton, and Others

Mayweather made headlines earlier in the summer for promoting ICOs, advising fans: "You can call me Floyd Crypto Mayweather."

Heiress Paris Hilton did the same, as have other celebrities across a variety of industries and areas, according to Fortune. Taken in a certain way, these celebrities are endorsing products in the same way that famous people have for decades. The key difference here, though, is that celebrities who link themselves with ICOs run the risk of running afoul of federal securities laws, which could potentially put them into hot water with the SEC.

Differences Between Endorsing a Product and an ICO

In 2011, the rapper and actor 50 Cent made headlines when he promoted a penny stock for a tech startup that he owned called H&H Imports on Twitter. The price of the stock rose in response. If the celebrity had sold off his shares at the higher price, he may have been subjected to a pump-and-dump investigation.

Mayweather, for his part, has pushed ICOs like Stox recently gained $30 million through a token sale. Besides Mayweather, soccer player Luis Suarez is also one of its vocal proponents. Paris Hilton spoke out on Twitter about a new cryptocurrency called LydianCoin.

As Fortune explains: "obscure companies with little more than a white paper are springing up and raising millions of dollars on the Internet...the question is whether these offerings are legal – and whether celebrities like Mayweather face trouble if they're not."

The SEC has already been attuned to the possible legal issues regarding ICOs. Earlier in the summer, the agency warned that digital tokens sold in an ICO last year were actually securities which should have been officially registered. In August, the SEC froze shares of four companies in connection with suspicion of pump-and-dump schemes related to ICOs.

ICO legal specialist Jeffrey Neuburger said if celebrities "know something is not right and they endorse it, there could be all sorts of fallout, including SEC action and even criminal charges if there is evidence of fraud."