(slang, vulgar) A gullible or easily-cheated person.
(derogatory) A stupid or contemptible person.
Verb
(transitive, obsolete, Britain) To strike in the face.
(transitive) To assault for the purpose of robbery.
(intransitive) To exaggerate a facial expression for communicative emphasis; to make a face, to pose, as for photographs or in a performance, in an exaggerated or affected manner.
(transitive) To photograph for identification; to take a mug shot.[1]
(Britain, Australia, slang) To learn or review a subject as much as possible in a short time; cram.
Noun
(slang, African American Vernacular)Motherfucker (usually in similes, e.g. "like a mug" or "as a mug")
