WINONA, Minn. — Mitchell Tiberius Foff, 25, of Winona, got a lesson on why not to make obscene gestures at the cops. Police had stopped Foff on Pelzer Street after a report that a man had fled a residence in 850 block of West Fifth Street after pushing someone down a flight of stairs at. On Pelzer, police gave chase to Foss, whom, they reported, threw them the finger. Foff, however, did stop at a red light. Police boxed him in and arrested him. The charge: Obstructing the legal process.