Affixes are normally added to the start or end of a word, where they’re called prefixes and suffixes, respectively. But sometimes they appear in the middle, as infixes...More at the link, and further discussion at another post there:
Infixation in English is often jocular or playful, as in “Homer-ic” edumacation, or Ned-Flandersy scrum-diddly-umptious, where diddly is infixed and um is reduplicated...
Another familiar form of infixation is expletive infixation, as in absofuckinglutely, where the infix serves to intensify the expression. Less rude is absobloodylutely, and milder still but retaining the structure is absoposilutely, which borrows posi from positively.
Infixes range from the barely noticeable to the very obvious. They appear as internal plural markers (spoonsful), as vowel links between bases and adfixes (speedometer), and in chemical nomenclature (picoline → pipecoline). They show up more arrestingly as intensifying expletive infixes (kanga-bloody-roos, absoschmuckinglutely, fan-fucking-tastic); as intensifying family-friendly infixes (scrumdiddlyumptious); in hip-hop’s -iz- infix (shit → shiznit, syrup → sizzurp); and as markers of casual vagueness (whatchamacallit, thingamabob) or “ironic pseudo-sophistication” (edumacation, saxomaphone).You learn something every day.