Correction: the second-greatest band in history, as the Chainsmokers hadn't been invented yet.
It happened during what turned out to be the Beatles' last tour in August 1966. Their opening act was to be this up-and-coming local band called the Cyrkle, made up of recent college graduates. They were in that sweet spot of being well-known enough to open for a big band but not famous enough to get recognized on the street. They also looked like they couldn't grow mustaches to save their lives. This must have also been the realization of six D.C. teenagers who decided that this was the perfect setup to pull off a Ferris Buellerian prank.
According to the 15-year-olds, they (rightly) figured that they needed a limo and a police escort so that the stadium staff would be sold before they even stepped out of the car. They obtained the first part by hiring a limo (and bribing the driver to keep his mouth shut) for the cost of $25.50 (or roughly $190 in today's money, so still pretty cheap). One of them accomplished the second by calling up the D.C. police and saying that their band was opening for The Beatles (and leaving from his parents' driveway) and needed a police escort. One of them also had his sister and her friend start screaming "It's the Cyrkle!" on the (once again correct) assumption that every girl standing outside of a Beatles concert is looking for an excuse to start screaming.