Two enemies are sharing a drink and one of the glasses contains poison. At least one of them will attempt to poison the other by switching glasses while the other's back is turned. Common joke is either that someone poisons a chalice, then they get switched over, or someone knows he's got a poisoned drink, and tries to find a chance to dispose of it without being obvious, or pretending to swap the glasses, waiting for the enemy to really swap them and drink. A less lethal variation is to shake up a bottle or can of soda or beer. Examples of Poisoned Chalice Switcheroo include: