The finale of the show's third season

"Clarence and Jeff Go West" is the thirteenth and final episode of Clarence 's third season. It premieres on Cartoon Network on June 29, 2018.

In the episode, Clarence starts mourning to have Sumo's company during school times, so he plans to get him and Jeff to West Aberdale to hang out with him.

This episode features Sean William Scott guest voicing as the series' new character, Andrew.

Plot
The episode starts at Aberdale Elementary, Clarence sighed when he had nobody to help him prank Ms. Baker. Clarence attempted to ask Jeff to prank her, but Jeff didn’t want to, then he asks Chelsea via note if she wants to, which she excepts. At recess, he writes his plan in the sandbox, which consists of putting a bucket of soda over the door the next day. On that following day, they attempt their prank, in which backfires when Ms. Baker exits the classroom, leading to Chelsea to drop the bucket on her. While they are in detention, Amy wonders what is going on with him, in which Jeff says that he misses Sumo's company on school times.

After school, Clarence has a plan to be with Sumo during school: pretend to be sick. Jeff doesn't want any part of skipping school, but fortunately, Clarence threatens to destroy his laser pointer if he doesn't, and he reluctantly goes along with his plan. The following day, they sneak inside West Aberdale Elementary into the cafeteria, much to Sumo's surprise. Taken to the bathroom without being seen, Jeff explains their predicament to Sumo, in which he goes along with. Throughout the day, the two are hidden in various places of the school; in either hiding in the sandbox at recess, on the top of book shelves in the library, or under the tables in the cafeteria. Unfortunately, they get caught by Andrew, the school's tattle-tale. Clarence and Jeff are brought back to their school and put in detention after the school and their parents had discovered their mishap. Ms. Baker warns them that if they ditch school again, they will be suspended indefinitely.

Four days go by, and Clarence had thought up a new idea to ditch school: get someone to pretend to be them. Jeff becomes distraught about his second plan and questions him on not explaining it earlier, in which he replies that he "wanted to wait long enough for everyone to forget about last time", much to Jeff's dismay. Bribing two kids that closely resemble them, they proceed to West Aberdale, disguised in the bushes, much to Clarence's realization that he hadn't brought extra clothes for them. During recess, they and Sumo talk, much to the students' confusion and wonder. Suddenly, Andrew walks up to peek into one of the bushes, but before he could, Ms. Lofton just received a call by Ms. Shoop that the impersonators were caught and had confessed about their absence, in which the boys pop out of their hiding places after hearing about it.

Later on, they get brought back to Aberdale Elementary to the principal's office, for their indefinite suspension, but Clarence refuses it as he explains his entire predicament about not having Sumo around during school times since his transferring. Mr. Reese then says that they can switch schools, too, much to their surprise, despite Jeff's suffering over the two attempts. Clarence and Jeff, now wearing the school's uniform attire, arrive at Sumo's house to pick him up. Arriving at West Aberdale, Clarence hopes that the next day will be better.