Three Men on a Horse (1936)

Erwin Trowbridge is a meek salesman blessed with the ability to predict winners in horse races. Even though he only dopes them out on paper and never actually bets, his wife is suspicious of his interest in horses and he's continuously bullied and browbeaten by his overbearing brother-in-law. Seeking solace in a few drinks in a local saloon, a trio of degenerate Runyonesque gamblers discover his talent and keep him a virtual prisoner in a room above the bar where they pressure him to continue to feed them his picks.