Top Secret Spy Strategy ((秘)スパイ大作戦 (Hi) Supai Daisakusen) is the fourth chapter of the Doraemon manga.
When Nobita breaks a vase belonging to his teacher at school, one of his classmates, Suneo Honekawa, uses this to blackmail him into doing work for him and becoming his slave like cleaning up classroom instead of the friends, buy some meat at butchery, and finding a ball in the drain. Suneo tells others about the "vase"; if anyone says "vase" Nobita must work for them and they use it to beg some money. Doraemon gets very angry when he hears and they decide to get Suneo back by recovering the broken vase and spying on him to discover his weakness with the Spy Set. After watching Suneo's activities during the afternoon, they finally find Suneo's weakness - wetting his shorts while sleeping - and decide to use this incident to blackmail Suneo back. Suneo angrily calls Nobita, who claims he had forgot about the "vase". He returns to school to find the broken vase restored. Frightened, he breaks it. Finally there are two weaknesses of Suneo, vase and diaper. When Nobita is told to use his hands to balance himself while barking half-naked, it is Suneo who does so instead when he hears the word "vase".