A long time ago, RetroMUD had a thief guild. This guild stole 
from other players.  Someone inevitably got angry and in some
cases quit the game, because player thieves were uniformly
1) big meanies, 2) stole other players' stuff.

A long time ago, RetroMUD had castle theft.  That meant 
that anyone could walk into anyone else's castle and steal
all their equipment.  Someone inevitably got angry and in some
cases quit the game, because castle thieves were uniformly
1) big meanies, 2) stole other players' stuff.

As a result, out-and-out theft is now banned from RetroMUD.
It is physically impossible to directly steal something from
someone else -- we coded it that way on purpose, and
everyone's happier as a result.  It IS possible for monsters
to steal from, you specifically the thief event.  

But there are other ways that players can "steal" from each
other.  They can steal "kills" by killing a monster another
PC beat to near death.  They can steal equipment left on
the ground when another PC is casting a spell or using a
skill on it (monsters can do this too).  They can simply lie
and trick a player into giving them something and then run
away.

Theft of this sort is bad.  It should be handled by the players
(if they are of similar level) or by Sentinels if the level
discrepancy between the two people involved is extreme.  

Theft is frowned upon on RetroMUD.  So don't do it.