Code Yellow

"Code Yellow" is another programmed trigger phrase used to control Jack by Frank Fontaine. Rather than triggering direct action, as the "Would you Kindly" trigger phrase did, this one triggers autonomic processes, specifically directing Jack's heart to stop beating. This doesn't happen immediately; as Fontaine notes, "The heart's a stubborn muscle, but it ain't that stubborn." The result is a series of periodic spasms that reduce Jack's maximum health, weakening him greatly over time. Fontaine uses this phrase to eliminate jack upon discovering that Dr. Tenenbaum had disabled the "Would you Kindly" trigger.

Jack eventually frees himself from this (and any other triggers that may have remained) by consuming a dose of Lot 192, thus restoring his maximum health to its previous state.