A gay man who attends circuit parties on a regular basis. It is usually a very expensive endeavor, since tickets to the parties are generally around $100 per event, and circuit parties usually take place on three to five consecutive nights in the the same city. The term often has a negative connotation.
He's getting to be such a circuit boy! He's been to three circuit parties this month! I don't know where he gets the money, or how he holds down his job -- he can't go into work sketchy every Monday!
Describes behavior that is erratic as a result of the use of rave/circuit party drugs (such as methamphetamine, ecstasy, ketamine, or less frequently gammahydroxybutyrate), or describes the person who exhibits the behavior.
"I saw him after the circuit party and he was big, sketchy mess."