The Legend of Zelda: Majora's Mask Tips

Bomb Bag Upgrades
Big Bomb Bag: Stop Sakon from stealing the bombs from the old woman at North Clock Town on 12:00 at night(stop Sakon with your sword and not your arrows or he and the bombs will explode until you play the song of time)and buy the Big Bomb Bag at the bomb shop in West Clock Town for 90 rupees.

Biggest Bomb Bag: After getting the Big Bomb Bag, go to Goron Village as a Goron and talk to the Deku Scrub there and trade your Big Bomb Bag for the Biggest Bomb Bag for 200 rupees(Biggest Bomb Bag originally priced at 100 rupees).