There was a post recently asking people for their favourite engagement stories, and I, of course, had to add my own, just because it was kind of bizarre (like most of my life, actually - hehe) I thought I'd go ahead and post it here, as well.
Several people were describing how their fiances surprised them with the proposals. Well, talk about "surprise" engagements - our engagement came as a surprise to *both* my then-boyfriend and me 
I've known Nyghtfall (his online name) since he was 15 and I was about 22, and over the years we'd gotten to be really good friends. About 6 years after we met, I had to have surgery on my right wrist, and since I'm right handed, it made a lot of things very difficult to do - typing messages in particular - and at the time, most of my social group was online. Nyght, being a sweet guy and a good friend, would come over every evening after work and let me basically dictate my responses to messages on the BBS's we frequented and typed them in for me, as well as helping out with some of the basic stuff that just needs to be done.
One night, he was giving me a backrub and it was so relaxing, I started to fall asleep. At some point, apparently, I started reaching up, running my fingers through his hair, and then pulled him down into a kiss. *I* don't remember doing that - that's how asleep I was! All I knew was I woke up and we were kissing, and something inside me just KNEW that it was the most right thing I'd ever felt. It was like the whole universe just suddenly clicked in place for me.
I had to drive him home that night, and on the way back, I heard Pearl Jam's song "Black" which has a line "I know someday you'll have a beautiful life, I know you'll be a star in somebody else's sky - but why, oh why, can't it be mine?" And I had to pull over to the side of the road because that's was exactly how I was feeling, and it made me cry so hard. It never occurred to me that he might actually want to pursue a relationship with me.
Thankfully, he did, and initially we said we were just going to date casually, but within about 2 weeks we realized that "casual" just wasn't cutting it and decided to be dating exclusively (not that either of us had gone out with anyone else during those two weeks.)
About a month after that, we were snuggled up on my couch, when Nyghtfall got this really blissful look on his face. I asked him what he was thinking and he said "I was just thinking how cool it would be if we could spend the rest of our lives like this." Assuming he was just making a romantic comment, I said "Yeah, that would be nice" - though I considered that to be mainly wishful thinking. The next thing I knew, he'd LEAPED up off the couch, and was bouncing around my living room, exclaiming "Oh my god! I'm getting married, we're getting married! I can't believe this! Oh my god!" and I was just sitting on the couch kind of "Uh.... ok... yeah... I guess that works...." and in a state of total shock.
After about a half-hour or so, he settled down, by which time the full implication of what had just happened finally hit me, and *I* started freaking out! It was really funny.
So, I've often said that when it comes to my husband and I, we started dating because I accidentally kissed him, and we got engaged because he inadvertently proposed 
Aw, what a sweet story! I think I would have freaked out too!