Green’s Dictionary of Slang

(US tramp) food left for a beggar outside the door.

1927		‘Jargon of the Und.’ in DN V 445: Exhibition meal, A hand-out placed on the porch or steps where the tramp is subjected to the stares of the whole world.
1930		‘Dean Stiff’ Milk and Honey Route 204: Exhibition meal – A handout eaten on the doorstep. The madam wants the neighbours to witness her generosity.