My headline is meant to be funny. A reader has taken us to task several times for using “for free.” This reader, Gerry from Chapel Hill, considers this phrase an error. Using “for” with “free,” commentators have said, is wrong because “free” as an adjective or an adverb cannot be the object of a preposition (for) and because the phrase is redundant. You just don’t need to say “for free.” It’s not the same as “for nothing.” Theodore Bernstein in “The Careful Writer” rejects “for free,” and so do other experts. However, “for free” is an idiom, and idioms[.....]