Examples:
In the early days, many features were specified by Not Yet Implemented, so NYI became its own term.
Error messages are meant to be awesome, so anything "Less Than Awesome" (LTA) was considered a bug.
Larry Wall didn't like the term "void context", so he invented "sink context" instead (with all the puns related to it, of course).
There were many more, though I have a hard time coming up with a longer list...