Five is my number.
Up to four, it’s just variations on fairly common sexuality - From coupling to swinging. Past five, the chance that someone in the room is having fun in some way you’re not aware of approaches unity.
I gotta go with five as well. With five, you either end up with a couple and a threesome of some combination, or a foursome with someone watching. That’s right the proper side of kinky, there.
Another vote for five. As has been stated, there are threesomes and a couple of couples, so five it is at bare (heh) minimum.
I think the US Army may have a trademarked slogan that conflicts with that … though they recently replaced it with “Orgy Strong”. 
Do you mind if I sig-afy this?
I can see the argument for four technically being able to qualify for an orgy, but I think I’ll have to go with five, too, just because five is the kinkiest number. Well, any odd number, really, but that dilutes my take on a classic saying.
It sounds like a real nightmare to organize, doesn’t it? 
For a true orgy, doesn’t at least one of the participants have to have a xmex-like snout and zymolosely polydactile tongue?
Four definitely isn’t, and six definitely is, so I guess it’s five.
This explains my thinking nicely. (Well, except that The Family Circus never entered my mind.)
True, but my neutronium-piercing claws play hell on the sheets.
A one an’ a two-
Five is the kinkiest number -
Five is the…
Look at it this way: what is the smallest amount of people hanging out together you’d consider a party? IMHO, five. And what is an orgy but a rather specialized form of party?
Droit de seigneur would do it for me.
As long as I was the Lord.
Three can have an orgy if two of them are twins.
I was going to v ote 4, but the thread convinced me to vote 5.
I went with 5 for the reasons listed above.
But I really think that would be a pretty tame orgy. To really put the “Org” in orgy you need 7+ couples. If you can do everyone there in a single night (for guys anyway) what kind of orgy is that? To really get the true effect, it seems to me (based on no actual experience you understand) you have to go home thinking next time you’re gonna be getting some strange.
YMMV
The minimum number for an orgy is the same as the minimum number for World of Warcraft - 5
An orgy must have at least 6 people: masturbation, one on one, threesome, 2 couples swinging, 2 couples swinging with a lookie-loo
I don’t want to know what a “lookie-loo” is. Welcome to the SD, aammyyrroossee!
Can the masturbator double up as the lookie-loo?