The Practical Joker

TAS Season 2 Episode 3
Air Date: September 21st, 1974

Plot

The Enterprise is surveying an asteroid field and just as they are finished they are ambushed by three Romulan battle cruisers. The Romulans claim that the Enterprise are in Romulan space while Kirk argues they are not. They notice an energy cloud nearby and they fly through it to escape. It works but then the crew start experiencing many practical jokes. Things from forks that bend to covering one deck with ice. They notice that the computer starts laughing at these jokes and Spock surmises that the Enterprise is infected by the cloud much like a person would get infected by a bacteria.

The ship even goes as far as taking the ship back to the Romulans and playing a joke on them. It creates a balloon version of the Enterprise that is 10 times bigger. The Romulans destroy it but get angry at being fooled like that.

Kirk takes a different tact, he pretends to be afraid instead of angry and gets the ship to go back into the energy cloud luring the Romulan ships into the energy cloud. Kirk effectively played a practical joke on the computer. The energy cloud reversed the effects, but now the Romulans are experiencing the practical jokes.

Commentary

This is the first episode where a holodeck is shown. It looks like it is a simpler version only able to simulate environments but until now the idea has never been brought up.