talk mode

n. A feature supported by Unix and some other OSes that allows two or more
logged-in users to set up a real-time on-line conversation. It combines the
immediacy of talking with all the precision (and verbosity) that written
language entails. It is difficult to communicate inflection, though
conventions have arisen for some of these (see the section on writing style
in the Prependices for details). Talk mode has a special set of jargon
words, used to save typing, which are not used orally. Some of these are
identical to (and probably derived from) Morse-code jargon used by ham-radio
amateurs since the 1920s. AFAIAC as far as I am concerned AFAIK as far as I
know BCNU be seeing you BTW by the way BYE? are you ready to unlink? (this
is the standard way to end a  talk-mode conversation; the other person types
BYE to confirm, or else continues the conversation) CUL see you later ENQ?
are you busy? (expects ACK or NAK in return) FOO? are you there? (often used
on unexpected links, meaning also Sorry if I butted in ellipsis; (linker) or
What's up? (linkee)) FWIW for what it's worth FYI for your information FYA
for your amusement GA go ahead (used when two people have tried to type 
simultaneously; this cedes the right to type to the other) GRMBL grumble
(expresses disquiet or disagreement) HELLOP hello? (an instance of the -P
convention) IIRC if I recall correctly JAM just a minute (equivalent to
SEC.... ) MIN same as JAM NIL no (see NIL ) NP no problem O over to you OO
over and out / another form of over to you (from x/y as x over y ) \ lambda
(used in discussing LISPy things) OBTW oh, by the way OTOH on the other hand
R U THERE? are you there? SEC wait a second (sometimes written SEC... ) SYN
Are you busy? (expects ACK, SYN|ACK, or RST in return; this  is modeled on
the TCP/IP handshake sequence) T yes (see the main entry for T ) TNX thanks
TNX 1.0E6 thanks a million (humorous) TNXE6 another form of thanks a million
TTBOMK to the best of my knowledge WRT with regard to, or with respect to.
WTF the universal interrogative particle; WTF knows what it  means? WTH what
the hell? double newline When the typing party has finished, he/she types
two newlines  to signal that he/she is done; this leaves a blank line
between  'speeches' in the conversation, making it easier to reread the 
preceding text. YHTBT You Had To Be There. Used of a situation which loses 
significant meaning in the telling, usually because it's difficult  to
convey tone and timing.