artful back-door backstairs calculating chiseling clandestine collusive conspiratorial covert covinous crafty cunning deceitful doggo FALSE falsehearted feline finagling foxy fraudulent guileful hidden hidden out hidlings hole-and-corner hugger-mugger in ambush in hiding in the wings indirect insidious lurking on tiptoe private privy prowling pussyfoot pussyfooted quiet scheming secret secretive sharp shifty skulking slinking slinky slippery sly sneaking sneaky stealing stealthy surreptitious treacherous trickish tricky two-faced under cover under the table under-the-counter under-the-table undercover underground underhand underhanded unobtrusive untrustworthy waiting concealed wily