Florin_Andrei refers to so called scare quotes. Wikipedia explains them as follows:
"Scare quotes are quotation marks placed around a word or phrase to indicate that it does not signify its literal or conventional meaning."
Raphael is obviously right here (but mind that sarcasm is only one of scare quotes examples). Let me quote (w/o scare) Wikipedia again:
"Use of the term "scare quotes" appears to have arisen at some point during the first half of the 20th century. Occurrence of the term in academic literature appears as early as the 1950s."
It's only about academic existence, but even considering real existence, it won't be much earlier.