The EEUEUUEEH is a sound that gabbers tend to make during gabber meals. When the cooking and food preparation reaches a certain level of intensity, a gabber can let out this sound in response to the intensity. This is evidenced by the first gabber meal in 2016, when one of the chef's dance partners made a EEUEUUEEH after the chef threw a bowl onto the stove to start the cooking. There are also other things than can cause a EEUEUUEEH, for unknown reasons.
When a gabber dies, it's ghost can let out several loud EEUEUUEEH's in the surrounding area, often to nearby gabbers that have either caused the death, or not done anything to stop it. This was seen after the original gabber chef was shot, leaving out very loud EEUEUUEEH's to his dance partner that didn't save him.
One mystery left unexplained is that in the first gabber meal, the dance partner made a EEUEUUEEH without moving his mouth. This suggests that gabbers may have some control over overnatural forces, along with their ghosts emitting EEUEUUEEH-s immediately after a gabber's death.