Cleo: "I know! It's a pizza!" (chews flat beach ball) "Yech. Definitely not a pizza..."
Pretty much the whole episode "An Itchy Patch", especially this scene:
Veteranarian: He seems to have a rash. Clifford:(Oh, Crap! face)
From "Flood of Imagination":
Clifford: Okay, so if we're going to the ogre's castle to rescue Emily Elizabeth, we should take a few things with us. Like a picnic. Cleo: And some games! T-Bone: And CAKE! Clifford: And some maps. Cleo: And an inflatable swimming pool! T-Bone: And CAKE! Clifford: And gas for the car. Cleo: And 27 pogo sticks! T-Bone:And CAKE!
In "Cleo's Fair Share", Cleo imagines herself, T-Bone, and Clifford playing with her new chew toy. She imagines T-Bone getting it covered in saliva and Clifford swallowing the toy due to his huge size. The best part is how unapologetically she imagines Clifford would say "Oops."
At one point, Clifford, T-Bone, and Cleo are making funny faces at each other. T-Bone turns around so he can properly adjust his face. The result? A mildly-angry face with his tongue sticking out.
In "Jetta's Friend", Jetta's pen pal from the city is visiting and Jetta plans out the entire day and uses a timer to keep track of time. After a bird steals it, drops it, and breaks it, Jetta responds, "This was definitely not part of the plan."
Birdwell Island, as shown in a weather map in one episode, is literally shaped like a dog's chewing bone.
In one episode, the dogs make the mistake of playing in a field where there happens to be stinkweed growing, causing everyone on the island to shirk away in disgust. As per usual, Cleo refuses to take a bath and instead suggests that they all take a sand bath, hoping it would somehow rub out the stench. Instead it seems to only make things worse, with everyone on the dock backing away and telling him to his face to take a bath. Even Cleo throws in the towel after that plan fails.
Clifford getting tie-dyed, with the dogs mistaking a set of paint bottles for shampoo when they help him take a bath. Each paint color causes Clifford to laugh harder and harder as they tickle his fur, before his entire back end is now rainbow-colored.
In one episode, Jetta spends an entire episode with her mother trying to get to Titanic Tower in the city, which is supposed to offer spectacular views of the area. While Emily and Clifford enjoy an entire day back home enjoying the island's simpler pleasures, Jetta and her mother encounter nothing but trouble the entire way, and finally make it up to the building only to have their view ruined by a fog. Jetta's mother makes very clear she has no intention of ever repeating that trip again.
Charlie and Emily using Samuel's ice cream maker to serve the customers on the pier, only to find the entire place flooded with ice cream when the machine jams. The thing dispenses absurd amounts of ice cream, which washes the customers away like a tidal wave and is eagerly gobbled up by the dogs.
Emily and Charlie's attempt to make perfume with Jetta's help as part of a Mother's Day gift for Emily's mom. Jetta's idea of making perfume is simply mixing up all of the sweet or delicious-smelling things they could find, including flowers, pine needles, cookies, bread and chocolate, even Clifford's bone gets added to the mix. Turns out the process is far different than what Jetta understands, and the end result is an absolutely foul-smelling concoction that only results in wasted food.