Edit
A bizarre sexual setting loosely based on wolf behavior, mainly used in slash/yaoi settings.
Humans are split into one of three biological categories: Alpha (Dominant species, may have actual wolf biology), Beta (Subservient species, humans as we know them) and Omega (Lowest rung, both genders are capable of getting pregnant by Alphas).
While this is a setting primarily used for fanfiction, there have been visual novels made on the subject.
See also
Nobody here but us chickens!