>>29355874 (OP)
It's quite easy actually, if you are in a part of the world with a swinger/kinky/BDSM scene.
There is plenty of website, parties and club.
And in a gangbang setting you can usually fuck girls who are usually quite hotter than if you were to meet them 1-on-1 because usually women don't need to be attracted to the men fucking them, their excitation comes from the act of being gangbanged.
People mentioned Fetlife, but if you are outside of the US there is plenty of local website, like JoyClub in Germany, Wyylde in France, etc...
SDC.com is an alternative for people who travel a lot.
In places where it's legal ( like Benelux, Switzerland or Germany) there is also a lot of gangbang parties with a mix of escort and libertine.
Source : i've been organizing gangbang for a living since 2012.
Each month i have a 100 people party ( 1 women per 3 guys), and about 100 gangbang/bukkake a year.
It's not very hard to find a gangbang, the hard part is about finding a "good" gangbang party .