This is also called dystmesis.

When you drop an infix into a word to amplify emotion, it’s tmesis. The example Dennis gives of “abso-bloody-lutely” is tmesis. “Whole nother story” is another common example of tmesis.

Dystmesis happens when you infix, but you do it in an unlikely place or with unexpected words.

“Un-fuckin-believable” is tmesis but “unbe-fucking-lievable” is dystmesis.