'To patter flash' definitions:

Definition of 'To patter flash'

From: GCIDE

Patter \Pat"ter\, v. t.
1. To spatter; to sprinkle. [R.] "And patter the water about the boat." --J. R. Drake. [1913 Webster]
2. [See Patter, v. i., 2.] To mutter; as prayers. [1913 Webster]
[The hooded clouds] patter their doleful prayers. --Longfellow. [1913 Webster]
To patter flash, to talk in thieves' cant. [Slang] [1913 Webster]