The Laugh Machine is an imaginary object that was in the mind of SpongeBob SquarePants. It appeared in the episode Funny Pants. The Laugh Machine scared Patrick and Sandy in his thought because the laugh was generated through a small balloon.
It also appeared in the episode Suction Cup Symphony because Patrick's bones were broken, and SpongeBob decided to be Patrick's doctor. One of the doctor ways for Patrick was using the Laugh Machine. However, Patrick took deep breaths instead of laughing.
The Laugh Machine is made of metal and it is in a thick cylinder shape.
Sandy: Hey Patrick! You wanna hear a joke?
Patrick: Sure Sandy!
SpongeBob: Sure, I love a good laugh!
Sandy: What has 4 wheels and flies? A garbage truck! (They laugh, but SpongeBob's laugh is generated by the machine and Patrick and Sandy slowly back away.)