Roblosexuals are usually exclusively attracted to characters found in the game Roblox. Most of the time they usually want to engage in sexual intercourse with Roblox characters. In game, or irl.
Guy 1: "You know Greg right?"
Guy 2: "Yeah, isn't he the Roblosexual"
Guy 1: "Yep, he fucks Roblox characters, and nothing else"
Guy 2: "What a sick motherfucker"
Generally speaking, someone whose primary sexual orientation is towards robots. They may be human or synthetic persons, and straight, gay, bi, etc is not specified. (Unfortunately, this word is often confused "romosexual," which is the only word that refers to someone who is both gay and a robot.)