But tell the truth, don't you sometimes do this? Let's say you've been working hard all week and tomorrow you're off. Then your friend calls the night before and asks if you can get up early and drive him somewhere. Or you're looking forward to your day off, and your friend calls and says he's moving the next day and needs your help carrying stuff. You'll be like, "no," at first, even though you know you probably will help. But you just have to throw that "no" out there in case it works and they find someone else, yet you know it won't.