Chuck Wiki
KGB pen

The KGB Knockout Pen, introduced in Chuck Versus First Class, is a gadget purported to have been issued and used by the KGB to incapacitate enemies.

The "pen" resembles an ordinary ballpoint, but when clicked it releases a stream of fast-acting tranquilizing fluid, which can be used to contaminate an enemy's food or drink.

In the episode, Chuck is given the pen by Daniel Shaw, and attempts to use it to knock out Hugo Panzer on a plane flight to Paris. Due to the pressurized cabin, however, the pen malfunctions, but eventually Chuck is able to use it to knock Panzer out when he sprays it directly into Panzer's mouth.

It has significant disadvantage. Unlike a tranquilizer dart, its victim is unconscious, but not deeply so. Panzer was unable to awaken after stimulus is applied (e.g. a shock).