Gahaha! The Exploding Lunchbox! is the 10th episode of the Katekyo Hitman Reborn! anime.
Lambo is given the simple task of giving Tsuna his lunch by Nana Sawada, but when he bumps into I-Pin, who was carrying a box of nitroglycerin, he ends up confusing the two boxes. I-Pin, realizing the mix-up, comes to school and holds two identical boxes. Lambo makes fun of her for mixing up the boxes, causing her to become embarrassed. She goes into her countdown, but is thrown away by Tsuna in Dying Will Mode. I-Pin drops one of the boxes, but Tsuna catches it and finds it to be his lunch. Later, Bianchi suggests that someone should be Lambo's babysitter. Reborn holds a contest where whoever makes Lambo smile would become Tsuna's right-hand man. Gokudera, Yamamoto, Ryohei, and Haru all fail and Tsuna is declared the only suitable babysitter. Tsuna comes home and sees Shamal there holding the box of nitroglycerin and shaking it dangerously side to side, mentioning how he found Tsuna's "lunch" hanging on a tree.