The only African American who posted in this thread seemed to think that Sir is an African-American name. That alone is a good enough source for me. But if not for that, it is along the lines of title names that are popular among African-Americans, as LillieMae87 pointed out.
No, if Beyonce named her twins Floorlamp and Televisionset it would not still be just African-American culture. Please see my post in which I said that if she'd named him Boo Boo Bear, that would have been different.