Agent Q at the Mustache Cup.

The Chief's code name when he was a field agent in the days before CONTROL switched to numbers.

After KAOS agents tap into CONTROL's hotline to the White House, impersonating the President, promoting Maxwell Smart to Chief and busting the Chief to Agent Second Class, "Agent Q" returns to duty, going undercover as a singing waiter at "The Mustache Cup", a restaurant which is a front for a KAOS communications center.

[Episode #84: "The Hot Line.]