A linguistics teacher of mine said in class that English is one of a small number of languages that uses infixes, that is, additions to the middle of words that alter the meaning. Most of the examples are profane, for example, abso-fuckin'-lutely or fan-fuckin'-tastic. When did these constructions first come about, and are there other instances that aren't profane? New to the site, please retag for more relevance.
Before taking a shot at an answer, we should be clear that there are different types of infixes.
When did this happen?
I seriously don't think there is an answer to this part of the question. If I had to guess, 1942.
Are there other less profane examples?
Of course! Put on a hip hop record and head hizouse, syzurp, dizamn and some other -z- infixes. Or, at a sad attempt at humor, some will say edumacation or sophistimacated. There are plenty, I'm sure I'll think of more on my way home. Will update later! More that come to mind: absoposilutely.
Until then, here's an awesome article on the subject. And for what it's worth, the correct (or debated) term for inserting a profanity into another word is tmesis (I couldn't think of it while originally posting this). This competing concept is why most would not call those infixations and why I think your teacher was heading in the wrong direction in this case.