Green’s Dictionary of Slang

mag n.5

[SE magpie, post-19C use mainly Aus.]

1. [late 18C+] talk, chatter.

2. [1910s] nagging.

3. [1910s] (Aus.) a lie.

4. [1940s+] a chatterer.

5. see magsman n. (1b)

In derivatives

maggery (n.)

[mid-19C] (UK Und.) chatter.

In compounds

mag-pie (n.)

[late 19C] speech, conversation.

mag-stake (n.)

[mid–late 19C] money obtained by verbal trickery or fraud.

In phrases

chuck a mag (v.)

[mid–late 19C] (UK Und.) to work as a confidence trickster.

stow one’s mag (v.) (also drop magging, stow magging) [stow v. (1) ]

[mid-19C] to be quiet, to stop talking, esp. in imper. stow your mag!, shut up!

tip the mag (v.)

1. [mid-19C] to talk duplicitously, to fool a gullible victim .

2. [late 19C] to talk, to orate.