circle jerk

Short definition from Wiktionary

Noun

1. 1
   A group of people jerking off (“masturbating”) together (with or without interpersonal contact).
2. 2
   Any group or group activity indulging in excessive mutual praise.
3. 3
   An environment (especially an online community) in which people express or validate a narrow set of ideas and feelings.
4. 4
   A situation in which a group of people engage in self-indulgent or self-gratifying behavior, especially by reinforcing each other's views or attitudes.
5. 5
   A person who shares syringes when injecting drugs.
6. 6
   Alternative spelling of circle jerk.

Verb

1. 1
   to participate in a circle jerk