A threesome that does not arise from any plan but rather through continuous or natural development, ie of a night gone incredibly weird/wrong/good.

Caviat: In the spirit of Green revolution, the three of you plant a tree together the following day.
Guy 1: Did I see you with TWO girls last night?
Guy 2: Yup, an organic threesome, came out of nowhere.
Guy 1: And the bonus?
Guy 2: Of course man, it was Earth day. Planted a hemlock.
by Snufalufagussy July 26, 2010
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