Pump and Dump is when someone buys a stock then advertises, markets and otherwise persuades others to buy it until the stock goes up, and then sells it at a higher price. This is illegal with stocks. With cryptocurrency it is a gray area.
Kim and Floyd were paid to marketing “EthereumMax” (not to be confused with Ethereum) to their social media followers, a cryptocurrency that had only been alive for a month, developed by unknown programmers. Kardashian has over 250 million followers.
The coins went way up. The founders sold. The price went way down.
Now Kardashion and Mayweather are party to a massive lawsuit. They should have known better.