Cupertino Rainbow is a term that originated in the porn industry,used to describe the sexual practice of smearing dyed or colored fecal matter on the back of one's partner by application of the penis used as a "paintbrush" following anal sex. The coloring of the fecal matter is achieved by the insertion of small colored wax pellets or "rainbow drops" into the rectum prior to initiating the sex act. Once the pellets melt the colored fecal matter can be applied via fingers or penis. Some enthusiasts or "rainbow chasers" photograph the results of the act for display as art. This act can be seen performed in the 2006 sex tape "Some Whore Under the Rainbow
"she was pretty open minded , but would never allow me to try the cupertino rainbow with her"