The Main Party room is a location in Five Nights at Candy's.
The Main Party room seems like a to be a small area for customers to eat. Two strings of red, blue, orange, and green star decorations are hung above the area. There is a door with a sign that says "Kitchen". On the left side is a table with two upside down chairs on it.
You can tell, if The Penguin is on the move by having a look at the door with the "Kitchen" sign.
If it's open, The Penguin is already on his way to The Office. When The Penguin hasn't activated (yet), this door is closed.
Obviously, you can only check that, if you have the night vision switched on.