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