I know exactly what you mean. Another way of making them scatter is to yell "immigracion", kinda like separating the men from the boys.
If you need me, I'll be at the old Roach Motel, aka the good old USA. Remember the predictions from 20-30-100 yrs. ago that the starving, hopeless World population of color would one day become a swarm of Locust overtaking the Western Richee countries....
Who were those pronasticators?