Blindfold

From Wikihack

A blindfold is a tool that can be used to achieve temporary blindness. Using a blindfold is a good idea if you are about to encounter a monster that can do you harm with its gaze (floating eye, Medusa) or that can blind you (yellow light).

After gaining an intrinsic telepathy by eating a floating eye corpse, applying a blindfold is good for detecting monsters, such as that leprechaun who stole your money or those soldier ants you want to avoid. It's also a good way to defend yourself from the gaze attack of pyrolisks.

However, a towel is more useful than a blindfold since it also gives temporary blindness when needed and it has other uses, too.

Samurai, Rogues and Wizards each have a 20% chance of starting with a blindfold, allowing them to attempt the zen conduct.