slip one over on
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slip one over on (someone)
To con, deceive or take advantage of someone; to make a fool of or hoodwink someone. My little brother always thinks he can slip one over on me, but I'll be the one to get the last laugh next time! Beware of these street vendors selling tacky souvenirs. They're usually just trying to slip one over on you.
slip one over onInformal
To hoodwink; trick.