A friend of mine noticed a man staggering about in the Times Square subway station. A well-dressed Wall Street type, his coat was unbuttoned, a briefcase dangled from his hand and he'd obviously had one too many.
-Asked if he was all right, the man gave a slurred but affirmative response. However, my friend simply could not see someone brave the rough maw of a New York subway without trying to help. He followed the chap, and again asked, "Are you sure you're all right? What subway are you looking for? Do you need help getting home?"
At last, the object of his attentions snarled, in a low voice, "Leave me alone! I'm an undercover cop!"