In Pre-Alpha, there was a giant version of Theodore Peterson that appeared only during a nightmare sequence in which the protagonist is trapped in their house. The Neighbor looks in through the window and attempts to grab the protagonist, first by reaching through the front door and then by smashing the front window.
The giant version of Theodore returned in Beta 3 in which he is a boss and is much, much larger. The opening sequence for the encounter also plays similarly, except he looks in the window for longer, screams with a childish scream (which is lowered in pitch in the final build) and smashes the room with his hand instead of attempting to grab the protagonist through the window. He then looks around for a bit before frustrated standing up straight. There is also a house on his back which the protagonist must reach by making the giant Theodore unable to stand up properly. This can be achieved by using some of the giant objects in the area, such as hitting his face with a firework to stun him and using baseballs, a soda bottle and a bow and sucker-tipped arrow to hit him in the legs.
The giant Neighbor is on his hands and knees outside the players house. He will try to use the door to catch the player but to no avail. He then smashes the window and then reaches his hand in to catch the player. Apart from cheats, there is no way to prevent this. This happens when you get caught by the Neighbor or sleep multiple times. Afterwards, the second stage of the game will begin and the Neighbor will switch to "Advanced" Idle mode.
Beta 3 - Full Game
There is a strategy for defeating the giant boss Neighbor. First, after he destroys the house, the player must pick up a basketball or a box, and throw it at the large light switch on the wall behind them. This opens the gate blocking the toaster. After this, the player must go behind the wall, and climb the flashlight up to the radio, onto the shelf and into the left side of the toaster. They will then be launched up to the dangling platform, where they can flip the switch which causes the platform to start moving up the pipe. The player can also get on and ride up the pipe.
Once the player reaches the top, they can take an item from the shelves and destroy the window, which allows access into a bare bedroom. When they flip the switch on the wall, the floor beneath the room opens, and umbrellas fall from the ceiling. The player must grab one so they fall lightly, and then if they can float to the platform with the controls of the train. If they can't then they can go back to the toaster and, once launched in the air, can float down to it.
Once on the train control platform, the player must press the button and pull the lever, so the train will ride the track to the end, where it will destroy the house. Once again, the player must launch themselves in the toaster and float into the now-destroyed house. Then, they must take a candle from the room, and go to the firework in the cable's path. They can then ignite it, which causes it to fly and hit the Neighbor. This weakens him to halfway.
The player must then launch themselves with the toaster, and float to the shelf with the baseballs. After this, they must push a ball into the shooter that was used for apples in a room earlier in the game. This will launch it at the Neighbor, which causes him to drop to his knees.
After this, the player must, once again, launch themselves with the toaster and float down to the platform to the left of the Neighbor. Then, they can set the string of the slingshot on fire, which blasts the sticky dart at the Neighbor, which knocks him over so he's on his hands and knees. Finally, the player must once again launch themselves out of the toaster, this time floating to the porch of the house on the Neighbor's back. Once the player lands, they can simply enter the house, the logo appearing and, as such, ending the beta.