Somebody creates a new smart contract (token) with a funny brand or meme name, puts liquidity into a DEX like Uniswap and sends the token around to named wallets. Some people hop on the train and swap the token for ETH. The clue and actual scam is that you can't ever sell it. If you decompile the smart contract, only the creator address can ever transfer the token.
The whole play takes 10-14 days, they pull the rug in their liquidity pool and move the money to another wallet to start with a new token. The token I got scammed with ended up making 10 ETH profit, after all transaction costs mind you.