Just a quickie so I don't have to go dig it up again...
insert a new file under /etc/xinetd.d/ (under Ubuntu, anyway):
# default: on
# description: xinetd service to emulate Flash Remoting banner
disable = no
type = UNLISTED
id = dummy
socket_type = stream
protocol = tcp
user = root
server = /usr/local/bin/dumbdumbdumbdumbdumb
wait = no
port = 843
contents of /usr/local/bin/dumbdumbdumbdumbdumb:
echo "Oh, fiddlesticks..."
Make sure /usr/local/bin/dumbdumbdumbdumbdumb is +x