Love this answer on Quora:
If you want to insert ‘fucking’ in the middle of a word you know exactly where to do it. You say Colo-fuckin-rado, not Co-fuckin-lorado.
Even more surprisingly, if you want to insert ‘diddley’ in the middle of a word, like Ned Flanders from The Simpsons, you know where to put that and it’s not the same place. (Note: Flanders’s also duplicates a syllable so it’s slightly different.)
Still more surprisingly, the rule that explains this placement can be explained in terms of prosody which is an entire dimension of linguistic (and almost musical) rules that few people seem to be aware they use.
– (1) English (language): What are some English language rules that native speakers don’t know, but still follow? – Quora.