Green’s Dictionary of Slang

breg n.

[ety. unknown; poss. misreading of bug n.4 (4a)]

(US Und.) any form of counterfeit scar or wound used to help in begging.

[US]N.Y. Times 27 Jan. Sun. Mag. 4: All of them, like Fagin, train boys and girls to beg on the streets, after being disfigured with ‘bregs’.