Tennis Ball's Trebuchet made its first in "Getting Teardrop to Talk". Before Tennis Ball was killed by Blocky, he created a trebuchet. The trebuchet launched 8-Ball and Basketball so that the basket could be weighed down, much to the anger of Blocky because he didn't need to climb the tree to grab the basket. After Blocky kills Golf Ball, 8-Ball says they should use the trebuchet to launch the basket to X.
Tennis Ball first proposed the idea for a trebuchet in "Get in the Van" in order to get across the Evil Canyon to escape from Evil Leafy, but he was eaten by Evil Leafy before the plan could be followed through.
In "You Know Those Buttons Don't Do Anything, Right?", a remodeled version of the trebuchet is shown as Tennis Ball had to repair the lava damage. Fries comments that it looks more like a catapult. It is used to launch Are You Okay to the top of the building, but they end up flying over it and into a tree, which flings them back into the trebuchet. This continues several times until Puffball uses Fries to bring Are You Okay on the top of the building, making them win the contest.