A threesome is any sex act involving exactly three participants at the same time.
A threesome is not an orgy. Only tag orgy and threesome together if there is a threesome as a group within an orgy.
A threesome is not a gangbang. Only tag gangbang and threesome together if there are two separated groups depreciated in the content where at least one group is a threesome and another is a gangbang.
Note that for tagging purposes, futanari are usually counted as "female", and cuntboy as "male".
