Here's a link to show you how writers invent names for their characters.
Jay?
jays last name is Brosnan(jay brosnan).
jay z redfield is his name
His last name is Carter.
Carter is his last name.
no, his last name is Brosnan.
jay chipmunk
Harbuck
Beyonce's last name is still Knowles. She did not change her last name when she married Shawn Corey Carter, also known as Jay-Z.Her maiden name is Knowles and she still uses this last name although her married name would be Carter. (Her husband Jay-Z's legal name is Shawn Carter.)
I don't know if you can be a good rapper if your name is jay jay... I do know that B.A.S.E is BASE Jumpers stands for buildings, antennas, structures, and earth! =-)
carter
His full name is Shawn Carter.