Do Forbidden Acts Become OK If You Do Them Weirdly Enough?

Responsa Radio #25

There is a concept in Jewish shabbat law called "shinui", "change". Certain acts when done in the usual way may be considered disobeying the laws of shabbat, while doing those same acts differently, with a shinui, may be fine. What lies behind this idea? When should shinui be used, and when should it not be used?