Best explanation of NFTs that I've heard and I stole it from the comments on Ars:
You know those novelty certificates where you can "buy" a star? No one recognizes them, they have no legal backing, and no one thinks you actually own a star. Everyone realizes they're just silly fun.
NFTs are the digital equivalent, except because it's using blockchain technology, scammers are trying to convince everyone these worthless certificates are actually valuable commodities which will grow in price.
For people who can't stop tooting!