Today I witnessed a Human mating ritual that I had only seen tangentially referred to in the Techeun archives. It involves two Humans pressing their intake orifices against each other. It is most often brief, but more advanced forms involve the use of their mastication organs, and the exchange of the mild digestive secretions.
I witnessed two young adults touching orifices in this manner for some time. They were quite enthralled by it, and proceeded for several minutes, stopping only when they noticed me taking notes.