Hurray for Hooligan (1937)

Promoters Buster and Tom pick up a prizefighter with a knock-out punch but learn that he won't put up a fight unless he is mad, and the only thing that makes him mad is the sight of a bearded man. They arrange a fight with the world's champion and get great odds after the gamblers see their fighter's sparring partners slap him around unmercifully. The day of the fight arrives and Buster and Tom are full of confidence as they have hired a bearded man to set in the first row...but the man has shaved off his beard. But all is not lost as they steal a couple of toupees from ringside spectators and put them on as beards. Their fighter knocks out the champion, the referee, some policemen and himself before the mêlée is over.