Love watching the night sky. Constellations, shooting stars, satellites (Plymouth's of course), the space station, the moon, etc. Living out in the country growing up you can see everything when it's a new moon.
I remember I showed my wife a moving satellite for the first time, and joked with her that it was a UFO, she was calling her Mom and everything. It was rather hilarious!
Out side of that though, I have seen some pretty interesting things, so UFOs, pretty sure, but Aliens, no.
Like several others, there were movements that were just not typical, or sometimes even capable, for an aircraft to make (that we know about), and like others I live in an area with three military facilities and have seen all of the various military aircraft fly, and none of them, excluding the F35 maybe, could make those maneuvers, and most sightings occurred before the F35 was even a on the drawing board.
Very neat to watch.