sneaky, underhand, underhanded -- (marked by deception; "achieved success in business only by underhand methods")
furtive, sneak, sneaky, stealthy, surreptitious -- (marked by quiet and caution and secrecy; taking pains to avoid being observed; "a furtive manner"; "a sneak attack"; "stealthy footsteps"; "a surreptitious glance at his watch")
(TTS Sound)
