When I posted about the use of bloody as a highly informal insertion into Australian English words, I didn't know this form of expression is called an infix, until Anonymous commented on the post.
Since then I've discovered that this particular infix is a FREE morpheme (smallest unit of meaning) because it can also operate as a stand-alone word - that is, it can move freely within a sentence without being part of another word.
I've been told about blooming, which can operate in the same way, but has more of a British English tone.
And, just now, I was browsing HyperTextBooks and saw a mention of damn used in the same way - fan-damn-tastic - though I must say the particular example doesn't roll off my tongue as smoothly as our Aussie expression does.
But, best of all , I suddenly remembered arp-language! When I was young I could speak it quickly and fluently, but now I have trouble even remembering how it worked. But I think it involved inserting arp - an infix! surely an infix! - before any vowel that was sounded. For instance, bottle would be barpottle and camera would be carpamarperarpa. Or maybe it would have been carpamarpra, because we pronounced it camra.
A Wikipedia entry calls this language game Arpy-Darpy and says it is spoken in New Zealand. Well, I can attest that it has been spoken in Australia, though I don't know if anyone plays with it now. We called it Arp-language.