sneakv. creep, slink, skulk; behave in an underhanded manner; do something or take something in a furtive manner; inform (Slang); steal (Slang)

sneaksneak (snēk)
v. sneaked, also snuck (snk) sneak·ing, sneaks
v. intr.
To go or move in a quiet, stealthy way.
To behave in a cowardly or servile manner.
v. tr.
To move, give, take, or put in a quiet, stealthy manner: sneak candy into one's mouth; sneaked a look at the grade sheet.
n.