Actually this thread got me thinking about all the times it almost happened but I was too dumb to realize it. Although all of these were in college during periods of extreme drunkeness where I kind of just wound up going to sleep instead.

Like when I was in college at a party and at the time I had very long hair and she tried to get me in her room to practice braiding it.

Or the time at another party out and there were several foreigners (all woman) in my room joking and laughing with me and being generally lascivious but I didn't pick up on it until the next day.

Or the time at a bar that I'm 90% certain was probably a prostitute for various reasons in hindsight but I had a girlfriend at the time and turned her down despite her repeated coaxing and I was too young/drunk to understand what was going on (that was a weird one).