The only guy from UP I ever knew had been a game warden (fifty years ago before fancy titles were
devised.) He told me about a hunter presumably mistaking him for a deer, and shooting at him.
"What did you do?" I asked. "Gave him an extra navel." "What did the judge say?" "He said I
done just right." So in his case, "U.P." stood for "Umbilicus Perforator".