So following the great Flashlight Catastrophe of May 2016, Teddi has added several flashlight noises which you can purchase from the Store > Flashlight Sounds tab and the cost is 1 million cubes each currently. Once purchased you can equip the item in your Misc slot, which'll then make the noise with a short cooldown. We have some generic sounds currently and if you have suggestions for new sounds please post them, should be 5 seconds or less in duration. The system is still early days so may make some changes to existing sounds, and plan is to add more over time.
There is a known bug at the moment when swapping between sounds where the new sound won't play. Just make sure to change to a different item or "none" when swapping between sounds and you'll be fine.