Haven't see that question yet, but a drain is the pattern formed by streams, rivers and lakes in a particular drainage basin, where a drainage basin is the place where water congregates before finally it drains into some larger body of water, like a river or ocean. In the case of the Frank and Poet Drain, it's a drainage basin just off the Detroit River. It's east of Flat Rock at the end of Gibraltar Road where it terminates at Gibraltar Bay.
One of the trivia questions that got me was the one about color blindness, and which colors people cannot differentiate if they are color blind. The correct answer is Red and Green, apparently because that's the most common one. But there are 4 different types of color blindness, each type affecting a different part of the color spectrum. The REAL correct answer is "All colors", but that's the wrong answer. Oh, well.