Being captivated by the sexiness of Rihanna; regardless of sex, race, or background. To be Rihsexual can also be used as a way to describe something Rihanna-esque.
The attraction to anything that is considered "rad" or "radical". Typically a Radsexual favors the 90s and will often use a walkman with 100 skate brand stickers on it.
A Radsexual will also watch alot of Teenage Muntant Ninja Turtles on their tube tv.