A: How was your weekend?

B: I worked overtime, trying to fill the tall order of getting the project done on schedule.

Note: A tall order refers to something that is very difficult to do. Tall, since the middle of the 19th century, has been used for things large in amount or size, figuratively as well as literally. For “tall order,” the Oxford English Dictionary tells us that it is “slang originating from the United States, referring to something expected to be hard to achieve.” Sometimes, people also use “a tall task.”