Rihanna — Spends the Day with Rob Kardashian

0826_rob_rihanna_go_kart_splashRihanna and Rob Kardashian spent their entire Saturday together … going go-karting during the day (above) and hitting up Playhouse in Hollywood at night (below).

It”s interesting … the two were rumored to have hooked up all the way back in February, but nothing has been mentioned about the would-be pair since.

Rob is dating singer Rita Ora and the two recently got each other”s names tattooed on their hands.