RG Live WotLK 3.3.5a

https://www.wowhead.com/quest=7702/kill-em-with-sleep-deprivation#comments:id=921948

When picking up the Dark Iron Pillows for this quest, 10 Sleepy Dark Iron Workers (lvl 44 / 45 non elites with 178 / 185 HP) will spawn after some time.
Some minutes later another wave of 10 Sleepy Dark Iron Workers will spawn.
A few minutes after the 2 waves of Sleepy Dark Iron Workers Chambermaid Pillaclencher (a lvl 49 elite with 21380 HP) will spawn.
You don't need to kill the Sleepy Dark Iron Workers, they will despawn after some time (like tessae mentions below here), so it's just a matter of time before Chambermaid Pillaclencher spawns after you pick up the first Dark Iron Pillow.
After you kill Chambermaid Pillaclencher the Pillaclencher's Ornate Pillow drops on the floor.
Click on the Pillaclencher's Ornate Pillow to get Chambermaid Pillaclencher's Pillow (the item that starts Look at the Size of It!).

https://www.wowhead.com/npc=14636/chambermaid-pillaclencher#comments:id=919648:reply=436284

To clarify: After you kill her, a large, round blue pillow spawns next to her corpse. Click on that to get the quest-starter item. You do not loot the item directly from her corpse. Took me looting 77 pillows before she spawned. In that time, the mob of Sleepy Dark Iron Workers only spawned twice.

https://www.wowhead.com/npc=14636/chambermaid-pillaclencher#comments:id=936073

Let's try to clear up some misconceptions about this NPC. In order for her to spawn, you do not need to continually pick up and delete dark iron pillows. What happens is that as you start to collect them, an event starts. Two waves of 10 sleepy dark iron dwarves will spawn, then the Chambermaid will spawn. Just hang out in the barracks and keep the trash cleared and you should get it eventually.

https://www.wowhead.com/npc=14636/chambermaid-pillaclencher#comments:id=924124

Despawned after about 20 minutes.

https://www.wowhead.com/npc=14636/chambermaid-pillaclencher#comments:id=927567

On spawn says the following:
"Chambermaid Pillaclencher yells: Thieves! Scallywags! Rapscallions! Come face me gigantic pillas!"

Schläfriger Arbeiter der Dunkeleisenzwerge
Zimmermädchen Kissenquetscher

https://youtu.be/Gu29CrLxFN0?t=18
https://youtu.be/a8cmquwSpgw?t=104