Flipping through the literature racks at the Hallowe'en Information Centre, the first one that draws your eye is "Popping for Hearts: a Traditional Hallowe'en Game of Terror!"
The booklet doesn't offer any history about this alleged tradition, but it does explain the mechanic of the game in a terribly straight-forward manner: you cause the hearts of children to pop out of their chests! They call it "fear-induced coronary mass ejection", with points being awarded for distance, blood splatter, and other more esoteric factors, and points being deducted for any manual interference on the part of the player, presumably meaning cutting into them and pulling the heart out by hand.
Oh-kay.