The Naked Time

TOS Season 1 Episode 4
Air Date: September 29th, 1966

The Enterprise is being tasked to evacuate some researchers before a planet breaks apart. When they get to the planet, they find the researchers all dead and frozen (the planet has turned into an ice ball before falling apart). The cause of death of the researchers was due to odd reasons. One was strangled, another was taking a shower with clothes on when things got cold. 

One of the Enterprise crew, Mr. Tormolen broke quarantine protocols and exposed himself to some blood from one of the dead researchers. He was then infected with a complex molecule found in the water on the planet below that creates the effects of drinking alcohol. For some it makes them sad, others violent. Most just become silly. Eventually it will cause death.

The urgency created in the episode is that the Enterprise gets put into a decaying orbit towards the planet that is falling apart below due to drunk crewman messing with the engines. In the end they were able to create an antimatter implosion to kick start the warp core allowing them to escape the planet. It also put them into a time warp where they started going back in time, 3 days in this case. At the end of the episode Spock says that with this, they could travel back to any time and any planet should they need to, and Kirk says "We might risk it someday, Mr. Spock."

TNG has an episode at the beginning of the first season called The Naked Now which was almost the exact same theme. Unlike McCoy who finds the issue and cure by himself, the crew of the Enterprise D use historical records to find McCoys logs to discover his cure. Overall this one was the better of the two. Watching Sulu run around the Enterprise shirless with a epee alone made it worth watching.