Via a mailing list, two giraffes beating each other up:
I’m sure that an actual biologist could explain something about what this odd behavior signifies, and there’s probably some fascinating biophysics in the way that they whip their necks around like that.
But, really, in the end, my main reaction is “Dude! Head-butting giraffes!”
(YouTube, of course, provides a wealth of other fighting-giraffe video, including this oddly disturbing video of a bald guy beating up a stuffed animal in the snow, to the sound of “Afternoon Delight” by the Starland Vocal Band. The Internet is an extremely strange place.)