Rorikon means pedophile (Which is also known as "lolicon".).
The word "Rorikon" isn't English, it's Japanese, this is how it looks written in Japanese : ロリコン (You won't be able to see it, unless you have installed the Asian language pack)
If you don't know what a pedophile is : "Pedophile persons can feel an attraction to children of a different sex, to children of the same sex, or both."
Just a friendly tip, stay away from child porn.
Person A : I don't know what's wrong with him, but I keep on seeing him flirting with young girls.
Short for "Lolita Complex" in a pairing. The "lolita" is always female, and the other member of the pairing is always older than the "lolita." The lolita is generally underage.
Person A: Did you read the Albedo/MOMO roricon?
Person B: Yeah, that was really sick...
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi