Boom Guys are a type of red Shy Guy that have Bullet Bill launchers attached to their heads. They have 18 HP. They are found in Bowser's Castle (past) in Mario & Luigi: Partners in Time. They are loyal to Baby Bowser. If enough damage is given to one, the launcher will fall off and they will be unable to attack. On every turn after it loses the launcher, it will call a pair of Fly Guys to give it a new one. However, most the time it fails. Later in the game, there is a stronger variation called Elite Boom Guys.