ducks

This actually came out in May, but just in case you missed it, the research on very, very, very long and corscrew shaped duck vaginas and penises -- longer than the ducks themselves, and twisting in different directions -- is interesting and entertaining.  Not surprisingly, the extreme length of duck penises had already been discussed in a paper many years ago, but no one had ever bothered to look at the corresponding vaginas until Patricia Brennan got involved!

SCIENCE
In Ducks, War of the Sexes Plays Out in the Evolution of Genitalia
By CARL ZIMMER
Published: May 1, 2007
Male ducks may have such extreme genitals because the females do too.