An extremely complex physical, emotional, pyschological, and spirtual act in which two or more humans pleasure each other with their bodies, specifially, their genitals. Also useful for reproduction in when practiced between a male and a female. Humans, however, are the only species who have devoted so much study to the subject, espeically on the non-physical aspects. After centuries of study and observation, they have come up with this general definition:
We have no fucking idea how to define sex. But it's a fun way to pass the time.