Not really a date, and it's more funny than "bad", but when I was a poor kid just out of college, a friend and I got a group house and needed a couple randoms to split the rent. I was out of town for a few days when we were doing a roommate search, and my friend called to say he'd found someone who he thought would be a good fit and was ready to move in that weekend. This was all pre-smart phone so it's not like he could send me many details about the person, but I trusted his judgment and said "okay".
I got back on a Sunday night, but nobody was home at the house when I got there, so I decided to head to a bar that was a few blocks away. I had never had any luck meeting girls at a bar by myself (and still haven't to this day), but this night, there was an absolutely gorgeous woman all alone and I decided to go for it. We hit it off very well (she'd had a couple margaritas by the time I arrived, which probably helped), and after a few hours of truly great conversation, she suggested that I "walk her home"...in a manner that clearly meant she was interested in more than just being escorted. Heck. Yes.
We pay our tabs, and head out the door. The conversation continued while we walked, and being slightly inebriated, I wasn't paying too much attention to our surroundings. At some point, the thought of "hey, I also live down this street" crossed my mind, but it wasn't until a half-block from my house that a much more startling thought crept in. I stopped in my tracks, said her name, and asked "um...where exactly do you live? What's your address?". Of course...it was the same address as mine. I'd met my new roommate.
For a split second, the devil on my shoulder almost convinced me to shrug it off...I could tell her in the morning, I thought. But my better nature took hold, and I said "look, this is totally awkward, but I'm actually one of your roommates. I'd heard that you would be moving in this weekend but as you know I've been out of town." She immediately turned beet red, started talking about how embarrassed she was, and how obviously nothing was going to happen because of "boundaries". Of course, I completely agreed with her (at least externally), but the following year of being sexually frustrated roommates was one of the most agonizing experiences of my life!
