Sets the message that a player sees when he drops the object, or after he goes through the exit.
Function references and %-substitutions are allowed in drop messages, and are evaluated when someone drops the object. In function references, 'me' refers to the object being dropped, while %-substitutions that refer to the enactor (such as %n, %#, %p, etc) refer to the dropper.
This attribute is only meaningful for players, things, and exits, and will never be automatically triggered on other object types.
Examples: <object> @drop vase = You gently put down the delicate vase. <exit> @drop elevator = The elevator doors close behind you.