Venn Diagram - n/v - A sexual act involving five people, two of whom are men, and three of whom are women.
In a venn diagram, each of the men has one girl to himself. The remaining girl is shared amongst the two men, and is represented as the overlapping region of the venn diagram.
John and Chris: "Hey ladies, want to come back to our place and Venn Diagram?"
Stacey, Jane and Amy: "Sounds like an orgy baby...yeah, count us in."
Amy: "Shotgun being the overlapping region. I love double penetration."