hehe, you got the idea of what it means
Ricer or "riceboy", is some derogatory term, not racially, as some people think of it. Suppose meaning a car with unnessary items installed and/or placed on/in the car. (eg: Big tall wings taller than the car itself with no aerodynamic performance.)
Theres probably more to it, maybe some of the folks can speak or add a bit to this.
btw, this site might explain it more about ricers:
http://www.riceboypage.com/
-Tsui