Being able to say "Damn, the seeing just went bad, I'm backing down to 300x" (from 580x, in my newly-recoated but not yet well collimated Cave 6").
The grey foxes sauntering through the parking lot just ten feet from where we were set up. They spent most of the night over by the little house poking through someone's discarded bags looking for food.
The amazing procession of white ovals following the Great Red Spot in the South Equatorial Belt on Jupiter.
Mark Taylor's Santa outfit and string of red Christmas lights. He says the hat is very warm and he might just wear it at star parties year 'round.
The Horsehead through Rashad's 8" with my H-beta. We only suspected B33 with my 6" and David's 128mm (though IC434 was more obvious than usual), but the dark notch was fairly obvious in the 8" Newtonian.
Being able to see the Encke smudge in my 6", a first for me.
The fearless raccoon pawing through the KFC box in the cab of the truck until I noticed it and shooed it away, and the other one who jumped up on the hood of the truck and sniffed around my eyepiece case until I turned and noticed it two feet away from me and shooed it down (afraid it might just make off with my 7.5mm Tak, raccoons being notoriously intelligent animals).
The constant stream of Geminid meteors, up to about Sirius magnitude.
The luminous contrails making dim lines across the sky all night. These should indicate poor transparency (lots of moisture in the air) but that didn't seem to be a problem.
Three lanes in M82 in a Short Tube 80. M31 at 20x, with the dark lane and both companions easily visible, in the same scope.
Coyote karaoke from the direction of the Peak.
50 degrees at night, in December.
The Merope nebula filling the field in the Tak FS128 with a 30mm eyepiece. I've never seen the nebulosity extend so far.