'To pass around the hat' definitions:

Definition of 'To pass around the hat'

From: GCIDE

Hat \Hat\ (h[a^]t), n. [AS. h[ae]t, h[ae]tt; akin to Dan. hat, Sw. hatt, Icel. hattr a hat, h["o]ttr hood, D. hoed hat, G. hut, OHG. huot, and prob. to L. cassis helmet. [root]13. Cf. Hood.] A covering for the head; esp., one with a crown and brim, made of various materials, and worn by men or women for protecting the head from the sun or weather, or for ornament. [1913 Webster]
Hat block, a block on which hats are formed or dressed.
To pass around the hat, to take up a collection of voluntary contributions, which are often received in a hat. [Colloq.] --Lowell. [1913 Webster]