A pun is a form of word play that suggests two or more meanings, by exploiting multiple meanings of words, or of similar-sounding words, for an intended humorous or rhetorical effect. NetHack contains many puns - items or monsters that behave in ways not necessarily consistent with their real-world or mythological origin, but which make sense based on an ambiguous reading of the name.
- The Black pudding is considered non-vegetarian, presumably because some types of blood sausage are known as "black pudding".
- A cursed potion of gain level puns on the two different in-game meanings of "Level" to refer to both experience level and depth in the dungeon.
- The loadstone is a pun (dating back to early editions of Dungeons and Dragons) on "lodestone". Sadly, it has no navigational function, but only acts as a heavy load.
- The turn undead effect also derives from Dungeons and Dragons and causes undead monsters to flee. When from the wand of undead turning, it can also be used to revive corpses - a pun known as the "un-turn dead" effect.
- When polymorphed into a form that can eat metal, eating an amulet of unchanging causes you to revert to your natural form: it "un-changes" you. This is noted as a pun in the source code.
- The substitution of a level teleport trap for the vault teleporter in closets on deeper levels is a pun on the secondary meaning of "aerarium" as "sky".
- Levitating over a sink will cause you to "sink" to the floor.
The presence of so many puns is one of the challenges of translating NetHack into other languages.