https://dictionary.cambridge.org/dictionary/e...

mug noun [C] (FACE)

informal mainly disapproving

someone's face:

his ugly mug

https://www.oed.com/view/Entry/123327?rskey=b...

mug slang.

 a. A face, esp. an unattractive one.

1708   Brit. Apollo 13–18 Feb.  My Lawyer has a Desk, nine Law-books without Covers, two with Covers, a Temple-Mug, and the hopes of being a Judge.

1798   G. Colman Heir at Law iii. ii. 47  Never let him clap his damned ugly mug in these here doors again.

1824   P. Egan Boxiana II. 412  His mug was often disfigured with the claret trickling down.

1850   E. FitzGerald Lett. (1889) I. 200  I found A. Tennyson in chambers at Lincoln's Inn: and recreated myself with a sight of his fine old mug.

1895   G. Meredith Amazing Marriage I. xvi. 186  Look at old Rufus Abrane. I see the state of the fight on the old fellow's mug. He hasn't a bet left in him!

1930   J. B. Priestley Angel Pavement ii. 84  They were all tired of seeing his depressing old mug.

1955   A. West Heritage i. 16  This is for you because you've got such a funny little mug.

1986   ‘L. Cody’ Under Contract xvi. 59  What! Miss a chance to get your ugly mug in the papers!

Informally, mug = face.

(It's in Leo too: mug [ugs.]   - person's face die Visage)

no - it doesn't conjure up any thoughts of mugs.*

The most common collocation is almost certainly 'ugly mug.'

As their sample sentences, Oxford Learners has 'I never want to see his ugly mug again'; Collins has 'he managed to get his ugly mug on TV'; Cambridge just 'ugly mug' The most recent of the OED sample sentences is also 'Miss a chance to get your ugly mug in the papers!"

*edit: in fact, until your post #4, sebsn, and your follow-up #6, I don't think I'd ever made the connection in my head between mugs (=of coffee) and mugs (=faces). 'Mug' has multiple disparate meanings (to mug someone=to steal from someone forcefully, mug=fool, mug=face, mug=cup) and all those meanings are separate in my mind.

Re mug „Tasse“/„Gesicht“: Es kann durchaus sein, dass ein Zusammenhang besteht. Immerhin bezeichnete das deutsche Wort „Kopf“ ursprünglich ebenfalls ein Trinkgefäß (siehe cup und ähnliche Wörter in anderen germanischen Sprachen). Das wurde dann zunächst pejorativ und später neutral mit dem Haupt gleichgesetzt. Im Niederländischen wird kop auch heute nur negativ oder für Tiere gebraucht, die neutrale Bezeichnung für Menschen (und Pferde) ist hoofd.

FWIW, und ergänzend zum Zitat in #6 :

https://www.etymonline.com/search?q=mug

 mug (n.1)

"small, cylindrical drinking vessel, often with a handle," 1560s, "bowl, pot, jug," of unknown origin, perhaps from Scandinavian (compare Swedish mugg "earthen cup, jug," Norwegian mugge "pitcher, open can for warm drinks"), or Low German mokke, mukke "mug," also of unknown origin. Hence mug-hunter (1883) "one who enters sporting contests solely to win prizes" (frequently in the form of engraved cups), a term of contempt.

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#8 Me neither. The meaning mug=face reminds me a bit of mug=fool (maybe I'm imagining someone with a stupid mug?), but definitely not of mug=cup.

The OED says that they are probably related thus:

mug (=face)

Etymology: Probably < mug n.1 [=cup], perhaps in allusion to the drinking mugs made to represent a grotesque human face which were common in the 18th cent.