Bebebese is a language in the Animal Crossing series. It can be spoken by NPCs, and the player's character always speaks it. Bebebese sounds like a typewriter.
When NPCs speak Bebebese, usually they are saying something really quietly. This appears as small, faded gray writing in the text bubble. But in Animal Crossing: Wild World and Animal Crossing: City Folk, the player can choose to have NPCs speak Bebebese if they'd like to.