Rolling Stone reports the pair shocked the crowd at the 450-seat club with their surprise appearance, joining the tribute act for 1987's "Where The Streets Have No Name" and "Out Of Control" from their 1980 debut, "Boy."

"It was unforgettable and just insane," says @U2 founder Matt McGee. "I was just numb. Tribute Edge was standing right behind Real Edge and Tribute Adam was standing right behind Real Adam. There was such joy in their faces. I'm almost in tears watching how happy they were."

"It was mind-boggling," McGee added on Thursday. "Our whole crew has been trading texts all morning saying, 'Did that really happen?'"