BB becomes active on Night 2. Starting in the Game Area, he will eventually come to the Office via the Left Air Vent. With each of his movements, he can say, "Hello," "Hi," or simply giggle. BB will not show up on any cameras except the Game Area and the Left Air Vent, keeping his path of approach hidden.
Balloon Boy is the only animatronic in the game that will not kill the night guard, but rather he will make an annoyance of himself by disabling the Flashlight and Air Vent Lights all while a sound loop of him laughing will play until the player is killed or gets to 6am. If this occurs, the player is especially vulnerable to Foxy's attack, as he can no longer be stunned with the now disabled Flashlight. To prevent Balloon Boy from fully entering the office, the player must put the Freddy Fazbear Head on while BB is in the Left Air Vent, and wait for the sound cue that he has exited the vent. However, the player should be advised that the noise heard may possible be another animatronic entering or exiting the Office or vents. Once BB has left the vent, he will return to the Game Area, and his cycle will repeat. If the player instead pulls up the monitor while BB is still in the vent, he will enter the Office. Balloon Boy will remain in the Office for the rest of the night, rendering it nearly impossible to beat unless it is close enough to 6 AM or Foxy's AI is set to 0 on the Custom Night.