A 1971 kung fu movie starring Jackie Chan.
Plot: Jackie, playing a character named Jackie Chan, is the son of a restauranteur who forbids fighting. The landlord is a real meanie, and also seems to be associated with the local gangs of kung fu ruffians. Jackie meets a beggar, who turns out to be a kung fu master, and you know the rest.
The title comes from an incident in which Jackie's father catches him fighting, and makes him plunge his fists into a bucket of broken glass.
Amusingly overdubbed with English and way-too-loud and totally inappropriate sound effects. A campy delight.