An action in which a person forces another person to give them their wallet against their wishes, usually through the intimidation of a gun, knife, or bare hands.

Georgie, ya bloody mug, whaddya mean you bought the Sydney Opera House off a bloke up the pub?

Also mug punter, meaning foolish customer.

Mug (?), n. [Cf. Ir. mugam a mug, mucog a cup.]

1.

A kind of earthen or metal drinking cup, with a handle, -- usually cylindrical and without a lip.

2.

The face or mouth.

Thackeray.

© Webster 1913.