CHRISTOPHER: Next time we get this group together we’re gonna have to frisk for weapons.
LORELAI: Hand out gags.
CHRISTOPHER: Employ six individual cones of silence.
Christopher is referencing the comedy television series Get Smart, which was created by Mel Brooks as a satire on the spy genre. Maxwell Smart (Don Adams) is a bumbling yet successful secret agent, ably assisted by the beautiful Agent 99 (Barbara Feldon); they work for government agency CONTROL headed by The Chief (Edward Platt). The show ran from 1965-1970, but was in re-runs for many years, including on Nick at Nite.
A running gag on the show was the Cone of Silence – two clear plastic hemispheres which were lowered over Max and the Chief’s heads as a security protocol. They were supposed to render their conversations completely silent to onlookers, but constantly malfunctioned so that they usually ended up shouting loudly at each other while outsiders could hear better that they, and not infrequently had to explain to both what the other was saying.
In common parlance, to say a conversation needs a cone of silence means that it has to remain secret (even though the real cone of silence did anything but).