Deep breath...
So a few years ago, when me and DP were courting 
, we were at his place one night, very late, on the roof terrace. I went in to go to the loo and he shouted me back to say he could see a satellite I know, we're geeks so I came back outside.
While I was looking at the sky, a massive shape came across the sky right in front of my eyes. I said to DP, what's that? He said, what? I said WHAT.THE.FUCK.IS.THAT and he stood rooted to the spot with me while we watched it float silently across the sky for about a minute.
It was massive. Black, cylinder-shaped and completely silent. The silence was the scariest thing about it. It had a red marking on the outside of it, but I couldn't pay much attention, I thought I was going to pass out.
When it had gone, we were both stunned. We didn't speak for ages and then I cried. I didn't sleep all night long, and when I told people at work in the morning, I burst into tears again.
I've always wanted to see something, my whole life. But I wish I hadn't. It was the singular most terrifying moment of my life, and I'll never forget it.