4. To exclude someone from an activity, or to ignore a person.
‘Flush’ was standard ITS terminology for aborting an output operation; one spoke of the text that would have been printed, but was not, as having been flushed. It is speculated that this term arose from a vivid image of flushing unwanted characters by hosing down the internal output buffer, washing the characters away before they could be printed. The Unix/C usage, on the other hand, was propagated by the fflush(3) call in C's standard I/O library (though it is reported to have been in use among BLISS programmers at DEC and on Honeywell and IBM machines as far back as 1965). Unix/C hackers found the ITS usage confusing, and vice versa.
(The next cartoon in the Crunchly saga is 76-05-01. The previous cartoon was 76-02-20:2.)