Brown Balloon is an A-level pet which was available only for limited time event from April 18, 2014 to May 14, 2014 5pm GMT+9 together with Cony Balloon. It is no longer on sale and cannot be summoned, but players who have obtained the pet may still use it.
Many players reported that the pet does not give its XP Bonus effect. In fact, the XP Bonus effect is active, however there's no visual cues that shows the pet is giving its said "10-15% XP Bonus". Its actual bonus will be shown after all visual effects of points, coin, and XP bonuses are played over, where the collected XP amount suddenly changes into a higher number.
One of the special balloons the witch brought back with her after her relaxing island vacation. The Brown Balloon was incredibly popular there, with Brown's mysterious poker face capturing the hearts of the island's brave cookies.