[WPI]
1. An indication of confusion, usually spoken with a quizzical tone:
Wall??
2. A request for further explication. Compare octal forty.
3. [Unix, from ‘write all’] v. To send a message to everyone currently logged in, esp. with the wall8 utility.
It is said that sense 1 came from the idiom ‘like talking to a
blank wall’. It was originally used in situations where, after you
had carefully answered a question, the questioner stared at you blankly,
clearly having understood nothing that was explained. You would then throw
out a Hello, wall?
to elicit some sort of response from the
questioner. Later, confused questioners began voicing Wall?
themselves.