The Jack-in-the-Box is a special tactical grenade that is found in Call of Duty: WWII Nazi Zombies. It can be found in the Mystery Box on all maps and can be given to the player randomly through a Waffenbox in The Tortured Path. When thrown using the 'Tactical Grenade' button, it will attract any nearby zombies to the device, very similarly to the Monkey Bomb from Treyarch Zombies. When the song playing from the box finishes and the "jack" pops out of the box, it will explode.
Compared to the Monkey Bomb, the Jack-in-the-Box does much more damage, being able to kill zombies past wave 26 where the Monkey Bomb would only turn the zombies into crawlers. The Jack-in-the-Box also takes less time to prepare and throw, as well as being able to be cancelled. The Jack-in-the-Box also does not injure the user, allowing a player to safely stand near one. An interesting thing to note is that the Jack-in-the-Box almost always appears within the first 10 Mystery Box uses, even without using any Epic "Jack-in-the-Box Guarantee" consumables that were introduced during the Liberty Strike event. After the first Jack-in-the-Box that has been offered by the Mystery Box appears, the Jack-in-the-Box becomes harder to come by.
The Jack-in-the-Box shares the same activation button as the Pommel of Barbarossa, and one will replace the other if picked up.
The player used to be able to carry 6 Jack-in-the-Boxes with the Stormraven "Grenadier" Mod which was only supposed to double the player's lethal equipment but also affected the Jack-in-the-Box. This was patched after an update.