A shit talker is what 99% of people under25 years of age are, especially when around other "shit talkers" who like try try to impress other idiots of their age group, to try to appear "worldly" or "
knowledgeable" about something they know
absolutely nothing about. Shit talkers are silent around adults, (people over 35) because they realize that people who have lived a while have heard plenty of bullshit talk and are not
impressed by juveniles babbling bullshit.
See also: liar, punk.