The Cancelled Dimension is where people who did "illegal" things on the internet go to.
In its debut appearance in SMG4: Mario Is Cancelled., after Susan Wojcicki thought Mario was going to say the N-word, he is transported to the Cancelled Dimension. After getting 8 Receipts, he makes an apology video and then is transported out of the Cancelled Dimension.
Before reaching that sector, and if someone attempts to escape the ride, then the gun will appear and will shoot at the escapee-wannabe until the people return to the car. In the Twitter Sector, you can see people who did crimes on the Internet that harms humanity and now punished on Twitter.
The Clown Sector is the circus area. When reaching there, the person is forced to wear the clown mask. Then, the two clown emojis appear and hits the person, then followed by 2 Pepes who each are wearing a clown wig appears. If the person has done the following things: hit a clown emoji, who then shoots the person, and then hit a Pepe; then the person will be honored as Clown of the Year (although Mario mocked this and say that he didn't want to become a clown.)
Hurtful Memes Sector
The Hurtful Memes sector is where Cringe/dank/not funny memes are put. Donkey Kong is apparently a resident of this sector. This is also where people come to mock the person who got canceled.
The dimension also puts the canceled person in a room consisting of the like-dislike bar of the 2015 era YouTube. This is where people would get crushed to death by receiving too many dislikes unless they had a way of accessing the like-dislike button, as Mario has shown when he managed to click on the like buttons a lot more than the dislike button.
There is also a Slenderman-like forest where instead of just 8 notes, it was 8 receipts. Should the person be unable to find all 8 receipts and the forest clowns got them, they would be taken away when an unknown fate awaited them (just like what happened to Busby the Cat). If they managed to succeed, they could use the 8 receipts to teleport them to another room where they could make an apology video.
The final room before leaving the canceled dimension would be a video-making room resembling that of PewDiePie's first studio. In it, the person just had to say sorry for what they did. Once they did, an elevator would appear and it would take them out of the canceled dimension.