armageddon_bomb
Lit. "Planet Destruction Bomb"
A "gadget" from Doraemon. Essentially an atomic bomb that Doraemon (character) occasionally brings out when he goes mad or insane (especially when he sees a rat). Primarily serves as comic relief within the series.
Since the bomb only rarely appears, it's never explained why Doraemon possesses such a weapon despite that fact that he is supposed to be a "babysitting robot". The bomb is also never used in any more serious situations (such as life-threatening moments in the various Doraemon movies), mainly due to the kid-oriented theme of the series.
On Danbooru, the bomb is tagged as a nuclear weapon, because when the manga chapter was first serialized in 1974, the gadget was actually called a nuclear bomb.