From Yes! 50 Scientifically Proven Ways to Be Persuasive:

“Because” makes any explanation rational. In a line to Kinko’s copy machine a researcher asked to jump the line by presenting a reason “Can I jump the line, because I am in a rush?” 94% of people complied. Good reason, right? Okay, let’s change the reason. “Can I jump the line because I need to make copies?” Excuse me? That’s why everybody is in the line to begin with. Yet 93% of people complied. A request without “because” in it (”Can I jump the line, please?”) generated 24% compliance.