In this not-exactly-safe-for-work video, two tapirs (a jungle-dwelling mammal, related to the rhinoceros) go at it with verve, while a nice family watches and makes what I assume to be amusing commentary.
As Matthew Cobb at Why Evolution is True discovered, this is only one entry in a whole genre of tapir sex videos and tapir penis photos.
Previously: The truly horrific penis of the echidna
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.