Rug pull scams "pumping up" a new project, nonfungible token (NFT) or coin to get funding. After the scammers get the money, they disappear with it. The coding for these investments prevents people from selling the bitcoin after purchase, so investors are left with a valueless investment.
Very common on this market and this is why its always been sensible that you should really make that in depth research first before throwing up some money into any projects.