What is idiomatic distortion?

I find nothing on the web, and my linguistic texts are stored. Nonetheless, two teachers ought to be able to figure this one out. Distortion is to bend something out of its normal state. Idiomatic refers either (1) to idioms, in general, or (2) to particular variations, as in an individual's idiolect. Putting the two words together, I see two possibilities based on the two definitions of idiomatic. Defn. 1: It is unlikely native speakers will distort normal idioms they've grown up listening to and reading. ESL students, on the other hand, have a very hard time learning idioms. If you're teaching ESL, here's a site that might help you to teach your students common idioms and help them avoid messing them up: http://a4esl.org/q/h/idioms.html Defn. 2: If you're teaching native speakers, then "avoiding idiomatic distortion(s)" is a fancy way of saying "use standard dialect." They don't want the students to use slang, regionalisms, teen-talk, cyber-abbreviations and the like. Each of us has our own vagaries when we speak or write, but you're being asked to get your students to use broadcaster's standard English.