An
irritating-yet-
innocuous type of
trap in
NetHack. If you step on one of these, it
squeaks loudly and awakens/attracts nearby
monsters. In a lot of ways, this is probably by far the least of your worries in the untimely-demise-fraught
Dungeons of Doom, where some hapless
Wizard or
Barbarian is no doubt having their
brains devoured by a
mind flayer as you read this.
Squeaky boards can be desqueakified by the thorough application of a potion of oil, or a few dabs out of the mysterious can of grease. I'm assuming it's mumak grease, because there aren't too many other NetHack creatures I can see being boiled down and rendered.