A study was recently release about how to get people to comply. One group had commands - similar to the OP. The other had people ask nicely, using the word please and thank you. People commanded to comply immediately became resentful and stubborn - no surprise. Those asked politely 90% of the time complied with no issues. No rocket science there.

I watch a lot of Pro tennis, and when the crowd gets loud and crazy, rather than the referee yelling, shut up, they always use Please. Works every time.