Just tell em - ""America. Love it, or leave it.""
Blacks are not true Americans. (neither are the so-called "natives" if you look at the evidence). America in BC was first discovered by Whites, then colonized by Vikings in 1000, and then host of a Templar expedition to escape the Pope, and later on, the host of a full-scale conquest from Europe. The Africans were not forced really. They had every right to leave their villages when they knew the Europeans were coming to Africa, but they stayed and let their own village chiefs sell them out to the Europeans. Even so they are native Africans, and must love this country or leave it. The true descendants of American pioneers are who it is left to, not Africans, to better the country of America.