Sent someone to the wrong airport and he missed his flight. It wasn't entirely my fault, because at that time, the map of the area had some confusing markings on it rather than a clear indication that "This is the Area's Major International Airport." He called back threatening to sue me. I explained our escalation procedure to him and told him that, while I didn't blame him for being upset, he was welcome to avail himself of that procedure. As for his threat to sue me, well, fortunately or not, I'm "judgement-proof."