First recorded in writing toward the end of the 19th century in the United States, snuck has become in recent decades a standard variant past tense and past participle of the verb sneak: Bored by the lecture, he snuck out the side door.Snuck occurs frequently in fiction and in journalistic writing as well as on radio and television: In the darkness the sloop had snuck around the headland, out of firing range. It is not so common in highly formal or belletristic writing, where sneaked is more likely to occur. Snuck is the only spoken past tense and past participle for many younger and middle-aged persons of all educational levels in the U. S. and Canada. Snuck has occasionally been considered nonstandard, but it is so widely used by professional writers and educated speakers that it can no longer be so regarded.
1560 (implied in sneakish), perhaps from some dial. survival of M.E. sniken "to creep, crawl," related to O.E. snican "to desire, reach for sneakily," from P.Gmc. *sneikanan, which is related to the root of snake (q.v.). The noun meaning "a sneaking person" is first recorded 1643. Sneak-thief first recorded 1859; sneak-preview is from 1938. Sneaky Pete "cheap liquor" is from 1949.