Three main definitions:
1.) To say something insulting or rude about another person, either to their face or behind their back.
2.) To make a statement that is exaggerated or flat-out untrue
3.) To say something negative behind someone's back that you wouldn't say to their face.

1.) She likes to talk a lot of shit when she gets drunk, "That guy is a fucking creepy stalker", when all the guy did was try to start up a conversation with her.

2.) "I can skate so ill, I did a 50/50 to a frontside boardside and landed doing a manual" or "My cousin's best friend in high school was Tony Hawk, and one day I met him and we chiefed some killer bud together!"...statement made my a poser "skater" who can barely do an ollie while in place on a skate.

3.) "She's such a whore", said in a serious way, by a girl who is actually good friends with another girl who just happens to be dating a guy she kind of liked; a comment made out of flat-out jealousy or envy.

All general examples of what it is to talk shit.
by 'Fro May 31, 2008
1. To say something uncalled-for or rude
2. To say something for the purpose of instigating a strong (possibly negative) reaction
3. To speak lies behind a person's back
4. To make empty threats
1. "Damn your mom was good in bed last night"
2. "You're ex-boyfriend told me that his vacuum cleaner can give better head."
3. "She sucks all her boyfriend's friend's dicks!"
4. "I'm gonna break your kneecaps open and make you drink the fluid"
by Lila & Set December 30, 2004
when someone says unneccessary shit about someone behind their back
justin was talking shit to michael about how kelli doesnt need a winter coat, shes fat enough to keep herself warm
by kelli fucking hennessy December 3, 2007
1. When some body is saying something to someone about else that is NOT true( you could argue that if its the truth then its not necessarily "talking shit"

2. When someone is rambling on talking about things that don't make sense
1. Nikki: why are you talking shit about me to my sister?

Mollie: i just told her the truth.

2. Mr Dude: do you think trees can talk to each other? Like read each others minds?
Other Dude: stop talking that mad shit Mr Dude
by Dalindabear January 12, 2017
1. Just bull shitting around with words and saying crap you dont really mean.

2. Insulting someone.
1. Jeff: Man ima marry queen elizabeth, she's a milf!
Ted: Quit talkin shit man.

2. Jeff: Ted you suck so much that David Oreck is having a tough time outmatching you!
Ted: Fuck you bitch.
by Oz February 28, 2005
To have a random talk with some over nothing or have no meaning what so ever
we talk shit for hours but dont get anywere
by wokkie January 22, 2010
saying bad things about something or somebody.
why are they talking-shit about me?
by Paco Rivera March 17, 2005