slip something over on
slip something over on (one)
To con, deceive or take advantage of one; to make a fool of or hoodwink one. Hey, these aren't real pearls! Are you trying to slip something over on me? Beware of deals advertised online that sound too good to be true. They're usually just trying to slip something over on you.
slip something over on
Hoodwink, trick, as in Her lawyer tried to slip one over on him, but his lawyer wouldn't let him get away with it , or Don't trust Dan-he's always slipping something over on his customers. [c. 1900]