This skull activates the following hidden dialogue:
Pie is good (randomly). I'm gonna eat your balls for dinner (when a Brute is attacking you). I shall be the one to teabag you (when a Brute is attacking you). Rip it Homies (when you get killed). Oh no! My weak spot (when a Brute loses his shield or when you stick it with a grenade in his groin).
Hug me (when a Kamikazi Grunt chases you). He's a zombie (when The Arbiter gets up). He really just beat the shit out of me (when you melee a Grunt but he survives). Pray before you eat me (when you kill or stick a Grunt). Suck my dick (when a Grunt is attacking).
Dude, can I be your friend (randomly). I almost got an achievement (when you killed an enemy your ally was attacking). Arbiter when you go home, will you tell the lady Elites about me (in co-op when The Arbiter stares at one of the Marine guards in "Crow's Nest"). Chief, do you have any socks I can borrow (randomly). Now I really can... oh.. thanks Chief (when you give a Marine an explosive weapon).
That one called you fat, Chief (randomly). Friendly fire, dumbass (when you shoot him). I would have been your daddy, but a dog beat me over the fence (reference to Halo: Combat Evolved, also the name of the skull). Are they actually trying to kill us!? Chief! Put down that jelly doughnut (randomly).
Master Chief, can we be friends (when you stare at one). I.. I.. I think your sexy too (when you stare at one). Is this because of Reach (when you shoot at one). Why don't you just take a.. uh.. what is it called again?.. A picture that's it (when you stare at one). I will name my next child after you (when you give him a better weapon).
Remember, we're allies, you dumb piece of crap (when you shoot at him). Yikes (when an auto turret is thrown towards him). Well that sucks, but come (after Sergeant Johnson dies). You shot me fool (when you shoot at him). What do you gain (when you stick him with a grenade).
Are you done recovering (when a combat form spots you recovering your energy shields). "Burb" (randomly). I like coffee (randomly). Like water, i am (randomly). Show yourself (when cloaking used in "Cortana").
No skill or you suck (when your energy shields are down or when you die). You will show me what she hides, or I shall feast up on your balls (Gravemind moment in mission "Cortana"; originally he says "bones", but the skull makes him say "balls".