The only time I've ever seen something that could be constituted as a UFO, I was out in Concan with my sister and her family and my wife. That Friday evening my brother-in-law and I were sitting out in the driveway listening to you '80s goth Rock and drinking some beer. The night sky out there is really great because there's no light pollution whatsoever.
I had gotten up at one point to grab us a couple more beers, maybe take a piss, came back and he was like man I just saw UFO. I told him he was full of shit, but he points to the area of the horizon where he saw it, and we watched it for a bit.
Sure enough about 5 minutes later we saw multiple red orbs off in the distance moving oddly, disappearing and reappearing, etc. it wasn't aircraft lights and there weren't any sort of towers off in the distance.
We watched them for about 5 or 10 more minutes and then never saw them again. Never seen anything like it in my entire life, and on all the other times we were out there we'd sit up at night waiting to see say whatever we appear but no dice.
My immediate thought was maybe ball lightning, but there wasn't any sort of storm front and it was a completely clear night. Was pretty surreal though.