I was on an DC10 flight one time and this guy in front of me reclines his seat back the entire way moments after takeoff. Since the plane was practically empty I simply moved to another seat. When we landed it turned out to be a work colleague of mine. There was some common cause as we were both headed to the same event, but I had absolutely no idea whatsoever that he was going. I was coming from London and he was coming from the states, connecting at LHR.

On another occasion a colleague ended up sitting one row behind her boss and fellow employee who had attempted a clandestine (and inappropriate boss/subordinate) weekend getaway together. Talk about busted.