TLDR: I saw a cone of blue light in the sky.

So, I'm assuming this was a military drone, or an early prototype (2005-ish, and right next to Davis Monthan Airforce Base) and not a flying saucer, but:

My friends and I were driving through the Sonoran desert outside of Tucson AZ. It was pitch black, no moon, the stars were as bright as ever. I was riding shotgun and my buddy in the backseat tapped me on the shoulder and pointed out the passenger side window. I looked out and saw a cone of blue light moving through the sky parallel to us. When I say a cone of light I mean that in the way that a flashlight emits a big cone of light. We couldn't see what the light was attached to, and we couldn't see the light itself. Like, we could see the cone of light being emitted, but we couldn't see any actual light source if that makes sense. There werent any blinking lights like you would expect from an aircraft. We stared at it for a second. My friend mumbled something but the music was too loud to make out what he said. Suddenly, the light made a sharp turn, spun a few times, and then started falling into the desert. It didn't fall straight down, it fell like a leaf. Moving back and forth and sort of stalling in the air as it fell. That's the part that makes me think it was a drone. The physics of it just seemed way too lightweight to be an actual plane or anything (I know that when the stealth bomber stalls it falls like a leaf, but if something that big went down in the desert right outside of town I think we would have heard about it.) When it hit the ground, there was no sound or a big fireball or any indication of an explosion, it just fell into the pitch black desert and vanished. I know that's probably not the craziest UFO story you can find on Reddit, but it was by far the strangest thing I've ever seen in the sky.