Dancing Grunts

The Dancing Grunts is an Easter egg in Halo 4 's Spartan Ops. The easter egg is only accessible in single player play on All The Secrets level on Legendary difficulty.

Walkthrough
At the beginning of the mission make your way to the second level of the facility. This can be done most easily by scaling the rock ledges on the right side of the map and/or by using a jetpack. Upon reaching the second level head over to the left side. At the top of the ramp you will find a human loudspeaker. Destroy the loudspeaker, then kill all of the Covenant on the lower level. Once you kill them all you will receive a prompt to open the door on the lower level. Upon entering, you will find eight Grunts dancing in a circle. Three loudspeakers have also appeared and are playing up-tempo music to which the Grunts are dancing. These loudspeakers cannot be destroyed.

Killing a Grunt will not cause the others to turn on you, however if the player merely wounds one, that individual Grunt will turn on the player.