You realize they changed the rules this year, but delayed implementation? The threshold used to be $20,000/200 transactions, but it's going to $600 for even a single transaction.
Your friend sends you $1000 for a shared vacation? That's a 1099-k.
Your roommates send you $1000 as their share of the rent? That's a 1099-k.
Sell your car for $5,000? That's a 1099-k.
None of those are actually taxable, so you need to sift through the 1099-Ks you receive to see which ones need to be reported and which ones don't.