The Fart in a Balloon is an accessory that combines the effects of the Fart in a Jar and the Shiny Red Balloon. It boosts jump height by 75%, increasing your first jump's height to 10½ blocks, and provides a double jump that now travels 18½ blocks, for a total height of 29 blocks. Unlike most other double-jump balloons, the Fart Balloon jump will put you at risk of taking minor fall damage if you do not cancel it before or at 25 blocks or have a Lucky Horseshoe. The jump also makes a fart sound every time you use it.
The Fart in a Balloon can stack with separate double-jump items, such as the Sharkron Balloon and Cloud in a Bottle. Stacking multiple items that give the same type of double-jump (in this case, Fart) will not increase the effects of the jump.