Sometimes when a band has a new album, they’ll arrange to play a secret gig to road test the new material. They’ll arrange a show under a fake name and then watch to see who shows up. If you’re a hardcore fan, you can often spot these gigs in time to be there.
For example, if you were in London in January 1991, you might have seen a notice for a concert by a band called Five Imaginary Boys. Had you turned up, you would have been treated to a club show by the Cure. In December 1997, the group billed as the Honking Seals at a club outside of San Francisco turned out to be Pearl Jam. And this would have been cool: Faithless and the Wonderboys in Reading, England, in February 1994. That was actually Radiohead playing a secret birthday party for their manager.