[afterburner]

Is it because 'tick' is a word? Or because it's nicer to have 1-2-2 syllables rather than 2-2-1? Or because 'tic' is the least stressed syllable in the word 'fantastic'? And the middle syllable is the most stressed, so preceding it with 'fucking' feels nicer?

[kissickas]

I would abso-fucking-lutely agree with your stressed syllable theory.

[StavrosK]

I find it very likely that it has more to do with the word "fantastic" than the word "fucking". "Fanta-fucking-stic" sounds very awkward.