Silly Balloon Machine is an item that Party Girl NPC sells. It produces balloons when placed. The balloons can be different colours. Those balloons stopped when a block is over it. The balloons travel a few blocks upwards before it dissapears. the Party Girl NPC sells it for 5 Gold Coins. Silly Balloon Machine produces infinite amount of balloons no matter what. You can activate/deactivate it via wires.
Note: Silly Balloon Machines are only available on PC version of Terraria.