A Guy is an effigy(nominally of Guy Fawkes) displayed by kids in England in the period leading up to November 5, in the hope of collecting money. Normally mounted in a gocart/pram or similar for speedy getaway from rival gangs, irate shop-keepers etc. The custom (like all Bonfie Night activities) is under threat from massive promotion of American style witch/devil/scream/pumpkin Halloween stuff.