Step 1: A story begins in the real world. In this case, some Nebraska ranchers objected to the longstanding practice—approved by the Supreme Court in 1986—of the use of aerial photography to enforce clean water laws.
Step 2: Their elected representatives raise the issue.
Step 3: Somebody on Twitter mistakenly converts "aerial" surveillance into "drone surveillance."
Step 4: The conservative website PJ Media puts the error into a headline: "EPA Using Spy Drones to Fly Over Midwestern Farms.”
Step 6: Fox News' Megyn Kelly reports the rumor as fact, unsourced.
Step 7: The Daily Show mocks Kelly's report, but treats the use of drones as a genuine fact nonetheless.
Step 8: Republicans in Congress write furious letters of complaint.
Step 9: The story is by now a national controversy, without there ever having been a word of truth to it.
Four conditions made the rumor possible: