the.com/shell game

means A swindle (or a deceptive tactic in general) where attention is deliberately misdirected so the victim watches the wrong thing while the real action happens elsewhere.

from From a literal street hustle: a con artist shuffles three walnut shells (or cups) with a pea hidden under one, then bets onlookers can track which shell it ends up under. The trick is never speed — it's sleight of hand, palming the pea in and out, so no amount of careful watching lets you win. The game dates back centuries as a classic grifter's trick, and by the 1800s-1900s 'shell game' had slipped into English as a byword for any scheme built on misdirection rather than mechanics.