1. A complicated-seeming gadget, the purpose of which is nonexistent or difficult to discern. Popularized by comedian George Carlin in a skit where he explained that only in America was the patent for a left-handed cheese straightener already taken.
2. Something odd that can only be found in America.
Person 1: What the #$%&@ is that jumble of levers and pulleys supposed to be?
Person 2: Why, it must be a left-handed cheese straightener!