bitch session

noun, Slang.
1.
a discussion in which people complain or gripe, usually about a shared experience:
Their first date turned into a four-hour bitch session about their ex-spouses' lawyers.
Origin
1940-45; originally military slang, from bitch (in the sense ‘to complain’)
Slang definitions & phrases for bitch session

bitch session

noun phrase
  1. A meeting where complaints and grievances are voiced, esp by labor-union representatives; gripe session
  2. bull session (1960s+)