Club Errera Easter egg
From Halopedia, the Halo wiki
The easter egg requires the player to turn on switches located on top of two buildings, which then make the Covenant forces in Club Errera to start dancing to either Never Surrender or Siege of Madrigal.
Activating the easter egg
Wait until the waypoint on Club Errera is activated. Do not go to Club Errera, and do not kill anyone there. Fly to the hospital, and look for a platform with two trees on the main building (the one with the blue symbol at the top, not the one with the jammer in it), towards the bottom near the walkways connecting to the other buildings. Land on the platform and activate the green switch on the wall.
Upon returning to Club Errera, a Jiralhanae will act as a DJ, with multiple dancing Unggoy throughout the club. Three more Jiralhanae are found acting as bartenders to the left and right side of the club, as well as beneath the club entrance, who will sometimes start dancing like the Unggoy when the music stops. Never Surrender can be heard.
Siege of Madrigal
To hear "the Siege of Madrigal," head to the top of the Vyrant Tower where the club is located and land on the roof. Underneath the ducts next to the ramp to the metal platform is another green switch. Activate it and return to the club. Inside, the Covenant will start dancing to Siege of Madrigal. The Covenant will ignore the player and dance unless the player fires at them.
If the player kills any of the Jiralhanae or Unggoy, or destroys the communications jammer, the music will stop and the remaining Brutes will attack the player. If Never Surrender is playing the Unggoy will also attack the player; if the Siege of Madrigal is playing the Unggoy will continue to dance.
List of appearances