It wouldn't be the first time, and it probably won't be the last, but a public notice of a planned "orgy" at 2018's BronyCon was announced on FimFiction by user PsyKey. The announcement, which goes into highly-specific detail, including the date, time, and venue of the orgy, as well as what to bring, was deleted some time later after receiving attention from the community at large, so it is unclear if the brony sex party is still going forward as advertised. Below, we have copy-pasted the contents of the announcement, in the event you are planning your own orgy and don't want to have it at the same time.
At the time of posting, we had joined in the Orgy Planning Discord Server and learned that the venue is being changed, so you will need to stay in the loop to know where the event will be held.
Please note, Horse News is not planning an orgy at BronyCon, these are the details from a now-deleted announcement.
"Bronycon Orgy Info! · 6:57am
Many of you probably didn't think this would actually happen! Well, it is! With the help of some great people, who will also be the security team at the event, we have made this a reality and I'm expecting positive feedback and attendance!
Date - Friday, July 27th
Time - 8:30 PM to 11:30 PM
Location - Hyatt Regency Baltiimore Inner Harbor - Room Number will be announced later on the Discord!
Provided Items
100 Assorted Brand Condoms
9 8oz. Bottles of Clear Cum Lube
52 Latex Mint-Flavored Dental Dams
6 8oz. Bottles of Hand Sanitizer
144 (24 of each of the Mane 6) Temporary Tattoos (There will be a paper at the event explaining the usage of these.)
Bronycon Orgy Discord!
Before getting onto the rules, recommended items, and guidelines, I wanted to explain that papers will be in various places in the room to help explain a few things such as the tattoos which, as of right now, are there to indicate what sort of interaction you're looking for. Cock, Pussy, or Both. (This was meant to change, but I had no further information from the team member who proposed that change. It may change later, and that change will be presented on the Orgy Discord.)
Also, we can hold 30 people in the room max at any given point in time. The Discord is meant to help in this regulation.
Recommended Items to Bring
A towel.
A bag or other container for your belongings such as clothes and personal items.
An extra condom or two, just in case there's a shortage for whatever reason.
A sports bottle with hydrating liquid if you're not interested in using the cups and filtered tap/pitcher.
Older convention badge or similar identification to be placed on your bag or container to identify it as yours.
A state-issued Identification Card, otherwise you're not getting into the party.
Rules
Breaking the rules is subject to punishment, up to and including authority involvement should it be completely necessary.
No weapons or items intended to cause harm. (The only exception is the host/bouncer, for security purposes only.)
No illegal actions including but not limited to drug use, assault, grievous bodily harm, and rape. (Follow the federal laws of the United States and state laws of the state of Maryland.)
No video or audio recording.
No photography.
Do not write on other guests without consent.
Nobody under the age of 18.
Get consent before doing sexual actions with another guest. Consent should be clear and direct. You don’t have to be a robot about it, just be enthusiastic and not awkward.
No means no. No is not an invitation to try again.
Guidelines
Guidelines are meant to help you have further understanding and to direct you should you find yourself in a confused situation.
Be considerate of other guests.
Arrive clean hygienically as well as in any aspects you plan to partake in. (Clean colon for anal, etc.)
Please do not use more than 1 temporary tattoo unless instructed.
If you’re just observing, there’s no need to use a tattoo. Please use condoms, lube, and other protection provided if you intend to engage with a partner that requests those.
Please leave all belongings (excluding involved items that need to be checked) with the Keeper of Things.
It’s recommended that you come on a comfortable stomach as food will not be present.
Please use the provided cups (and markers to properly label your cup) and filtered tap/pitcher to keep yourself hydrated throughout the festivities.
Phones are allowed, but please do not be disruptive.
Changing is allowed anywhere in the room. The bathroom is also available.
Please join the Bronycon Orgy Discord if you plan to enter the party, as it helps us regulate how many people we’ll have in the room at any point in time. If you’re leaving, please tell a staff member on the Discord and we’ll change your status.
We ask that you do not die at the party.
If you have any questions or concerns regarding the event, you can ask me here or on the Discord group.
Psy Key"
The tradition of the BronyCon orgy (and the myths surrounding it) date back to at least 2012 and has it's own KnowYourMeme page.
As well as a definiton on Urban Dictionary.