The casual utterance of four-letter words among colleagues (a.k.a. "social swearing") allows co-workers to bond, while "annoyance swearing" (dropping an expletive in the context of doing business) can cut the tension in the office.
—"Bombing the office, coping with loss," The Globe and Mail, January 28, 2011
When the group was relaxed and happy, the swearing was clearly of a social kind, a sign of being "one of the gang."...Under conditions of very low stress, swearing was almost entirely of the social variety. With increasing stress social swearing diminished and annoyance swearing increased.
—Ashley Montagu, The Anatomy of Swearing, Scholarly Book Services, June 27, 2002
Here's a much earlier citation that refers to swearing at a social gathering, such as a dinner party:
Whatever happened to the foulmouthed women of 1970s dinner parties?
Now, in the Age of the Young Fogy, of political correctness on the left and family values on the right, you hardly hear social swearing at all.
—Henry Allen, "Expletives Deleted," The Washington Post, September 15, 1992