bull session 
noun North American
An informal group discussion: I heard sharper political talk in the all-night bull sessions...
- The program had a college bull session, rather than professional, atmosphere.
- The difference between PRI and NPR is kind of like the difference between a bull session with particularly astute friends and a lecture by a knowledgeable but vaguely condescending college professor.
- Now I can sit around the Round Table for hours rehashing last night's scores or dissecting the peculiarities of anyone not sitting within earshot of our bull session.
Origin
1920s: bull from bull3.