The clubhouse is mostly a cardboard box with a picture of a door drawn on it. In order to be able to enter, one needs to step on the automatic doormat. The clubhouse is located behind the Barg'N-Mart.
The interior appears to be much larger than the exterior. It is just one big room with cardboard walls. The walls have been fixed with tape in many places. On the left side of the entrance is a check with a cardboard door saying "CHeCK" in a purple font. The check also has a metal hook for the brains of the society's members.
Furthermore, the room has a wooden stage at the other end of the room. Left to the stage is a clock scribbled on the wall with the same purple paint. The clock reads "♪, 1, B, A, ☺, X." The stage has a toilet paper background, a sign with the letters "e.H.s" on it and a microphone, which consists of a broom with a roll of toilet paper mounted to the top end of the broomstick.
Next to the clock, there is a gramophone made of junk, which, instead of playing records, plays a turkey and later a piece of ham.
Also, the clubhouse has a shelf for the jars filled with the members' saliva for each meeting day and a portable lemonade stand.
Role in episode
SpongeBob and Patrick go here to see the Empty Head Society. They are required to take their brains out upon entrance. They are then given a fez to wear. Sheldon then approaches them and Patrick does the empty head handshake with him.
One of the club members than looks at a clock and drops a cinder block on himself to signal that a meeting is gonna start. Everyone then rushes to the meeting area. The Ice Cream King comes up on the stage and gets the secretary to read the minutes. His secretary comes out of the ice cream kind's belly and then reads off a Kelpo cereal box. Then the ice cream king kicks the secretary and then asks if there are any new initiates in the club. Patrick tells SpongeBob that since he is new, he has to go up on the stage. SpongeBob comes up, but the ice cream king is suspicious. However, SpongeBob slamming himself into a plank of wood makes the ice cream king convinced and gives him a badge.
The ice cream king then says that it is time to pass the jar and then some of the empty heads pour their saliva into a jar. Then they give it to SpongeBob to drink out of it, which he does, but everyone gets grossed out by it. The ice cream king then shows him the thing he was supposed to drink, which was the lemonade, but gives him another badge because he thought of SpongeBob's action as dopey. He then tells everyone that they will now be helping Bikini Bottom by doing their civic duty there. SpongeBob doesn't understand, but Patrick tells him they call it "The Nitwitting." Then the empty heads sing "The Nitwitting Song" and then go to Bikini Bottom to do their civic duty.