Hickory dickery docTOS; season four..
Kirk and Spock crash land on a planet where the citizens all speak in rhymes. Spock refuses to do so, and is put on trial, and could be executed. Only a great speech by Kirk, all in rhyme, can save his Vulcan friend.
Free Spock from the dock
It's no crime
not to talk in rhyme
If Spock doesn't go out the door
It general order 24
Hehe. Or...
KIRK:
Hickory dickory dock
Now give us back our Spock!
We can't invent slash
Without his fine... ash
Now here is a jig from our Doc!
MCCOY: Dammit Jim, I'm a doctor, not a dancer!