circle violation 

When you have sex with more than one person in a circle of friends or coworkers. This act may disrupt the natural balance of this circle of acquaintances, causing discord, animosity, and jealousy among the members of the circle.

Jane slept with both Ted and his best friend and former fraternity brother, Larry, which was a blatant circle violation. Although neither Ted nor Larry are interested in dating Jane, they no longer speak.

circle violation by sorkab February 11, 2010

Violating the circle 

V. To commence penetration of an orifice originally found in a person within a circle of friends, without other members of the group being privy to your carnal knowledge of the other person.

Mark in accounting is violating the circle by hooking up with Susie at the department's Christmas party.

Violating the circle by boredatwork11 May 18, 2011