There are two ways to surprise and delight fans with a secret gig.
(1) Assemble a bunch of people at a pre-determined time and place, telling them that they’re going to see a show by a big unnamed band. This was a favourite beer company promotion in the 90s (the Miller Genuine Draft Blind Date series) that saw great success by featuring bands like the Foo Fighters, the Sex Pistols and Stone Temple Pilots.
(2) A band just shows up and starts to play unannounced and often in an unusual location.
Of the two, I like the second one the best–although these sorts of performances tend to be extraordinarily rare. When the White Stripes toured Canada in 2007, they made a habit of playing a short gig in a weird place on the day of each show. I saw Jack and Meg play a YMCA daycare in downtown Toronto. They also played a bowling alley in Saskatoon.
The Telegraph has this list of 13 memorable secret concerts. It’s a decent list, but I can’t help feeling that a bunch are missing.