I remember a discussion about the censoring of swearing in TOS. Somebody suggested that Spock actually always said ‘fucking nuts dude’, ‘fascinating’ is just what the universal translator makes of it.
Anyway, I couldn’t find the discussion using search engines and I suggest you do not search for “spock fucking nuts dude”.
Universal Translator: “Captain, no one has ever encountered such a phenomenon.”
Translation from Vulcan: “Jim, this shit is wack, yo.”