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.
To photograph for identification; to take a mug shot.
To learn or review a subject as much as possible in a short time; cram.
Early 16th century (originally Scots and northern English, denoting "earthenware, pot, jug"), of unknown origin, perhaps from North Germanic (compare Swedish mugg ("mug, jug"), Norwegian mugge ("pitcher, open can for warm drinks"), Danish mugge), or Low German mokke, mukke ("mug"), German Low German Muck ("drinking cup"), Dutch mok, also of unknown origin. Perhaps related to Old Norse múgr and Old English muga. Compare also Middle English mug, mog.
"Face" sense possibly from grotesque faces on certain drinking vessels. "Assault" sense of verb possibly from hitting someone in the face.