In crypto and trading, a flip refers to quickly buying and selling an asset for a short-term profit. In the crypto context, 'the flippening' specifically refers to the hypothetical event where Ethereum's market cap surpasses Bitcoin's.
Example
“The NFT trader flipped a newly minted token by buying it at mint price for 0.1 ETH and selling it on the secondary market an hour later for 0.5 ETH, netting a quick 400% profit.”