Star Trek: The Original Series
The Naked Time
S1 E4:
An alien virus picked up from the now-dead Psi 2000 outpost strips the crew of their inhibitions, causing chaos as each individual is overcome by hidden emotions -- even Spock. Meanwhile, the disabled crew have left the Enterprise unable to react to the planet break-up below that is pulling them down.
Starring
Bruce Hyde, Stewart Moss, Majel Barrett