Comments

The nethack source code has some illuminating and embarrassing comments. Here is a selection, just to get you the feeling.

Illuminating

From pray.c for the function god_zaps_you, about what happens if your god decides to destroy you with a wide-angle disintegration beam but you are disintegration resistant.

/* "I am sometimes shocked by...  the nuns who never take a bath without
* wearing a bathrobe all the time.  When asked why, since no man can see them,
* they reply 'Oh, but you forget the good God'.  Apparently they conceive of
* the Deity as a Peeping Tom, whose omnipotence enables Him to see through
* bathroom walls, but who is foiled by bathrobes." --Bertrand Russell, 1943
* Divine wrath, dungeon walls, and armor follow the same principle.
*/

From the beginning of spell.c explaining how spellcasting penalties work. It's worth to check out the full comment there.

 *	Tou are aware of magic from all the great films they have seen

From trap.c in the mintrap function, on what happens if a monster falls into a trap made by you, or triggers a bear trap or land mine set by you.

        /* Monster is aggravated by being trapped by you. Recognizing who made
           the trap isn't completely unreasonable; everybody has their own
           style. */

Funny

In objects.c

/* "If tin whistles are made out of tin, what do they make foghorns out of?" */

Embarrassing

In spell.c function spelleffects, where it creates a stack of 20 spellbooks as a pseudo-objects that it passes to functions that normally expect a scroll or potion.

	pseudo->quan = 20L;			/* do not let useup get it */

In weapon.c function dmgval, when computing bonuses for blessed or silver weapons

	    /* if the weapon is going to get a double damage bonus, adjust
	       this bonus so that effectively it's added after the doubling */
	    if (bonus > 1 && otmp->oartifact && spec_dbon(otmp, mon, 25) >= 25)
		bonus = (bonus + 1) / 2;