# Yet Another Funny Message
Yet Another Funny Message (YAFM), also sometimes known as Yet Another Silly Message (YASM), is any funny message you might receive during the game. 
Intentional funny messages usually come up in obscure circumstances and are good instances of The DevTeam Thinks Of Everything. Many of them are hallucinatory messages. Some examples:

Oh look, what a pretty fire in your hands.
You read a scroll of fire while confused and fire resistant.
It seems even darker in here than before.
You created magical darkness from a cursed scroll of light, while swallowed by a monster.
Shame on you!
You tried to use a saddle on a foocubus.
You hear a faint typing noise.
You used a stethoscope on the edge of the map.
You be chillin'.
You gained fire resistance, while hallucinating.
YAFMC
When multiple unrelated things combine into a funny phrase, it is a YAFMC (Yet Another Funny Message Combination):

You are standing at the gate to Gehennom. Unspeakable cruelty and harm lurk down there.  Are you sure you want to enter?  So be it.  You fall down the stairs.
You drop an uncursed cockatrice corpse.  It explodes!
The little dog growls! "Halt! You're under arrest!"
You begin praying to Amaterasu Omikami. You are surrounded by a shimmering light. "Come here often?"
The Uruk-hai hits! Your leg feels better.
The Amulet of Yendor cannot be confined in such trappings. "Burrrrp!"
YAFP
The term YAFP (Yet Another Funny Prompt) is also occasionally used, which is when a prompt for inventory letters or something similar forms a word or other odd combination.

What do you want to eat? [chips or&nbsp;?*]
External links
The origin of all of these terms is probably rec.games.roguelike.nethack.

rec.games.roguelike.nethack: Shawn Moore: NetHack prompt words (YAFP)