Chuck's spy will refers to Charles Bartowski's testament, a precaution that a field agent takes in case of the Agent's death in the field. In the Chuck universe, a spy will is often sealed in a small circular box opened by a crypto key. The spy will is often left with the spy's family, friends, or loved ones to be opened in the event of the agent's death.
Chuck is seen making a spy will after Sarah gave him hers. The contents of the box are unspecified, except for the note as follows: