A wet thin string is pulled through a hole in the bottom of a plastic cup leading to spooky sounds.The sounds being created are from the air vibrations of the wet string and a plastic cup. The cup is amplifying the air vibrations that are being heard causing the eerie noises. Between your fingers and the wet string, friction is being implemented because the wet string supports the smooth glides.
https://www.stevespanglerscience.com/lab/experiments/screaming-balloon/
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