Okay so the short story is that in 1605, when this took place, Guy was just a first name. it had no other meaning. At this time, England was officially Protestant, but there were still some catholic supporters, including this specific group. They decided that they’d blow up parliament, including the king, his son, and many other officials, and that afterwards, they’d kidnap the the kings daughter (a kid at the time) and she’d be a figurehead catholic monarch. The plot failed due to a tip off. Guy Fawkes and the others were captured (except one who died in a shootout) and Guy Fawkes became the most famous member. To this day, the UK has Guy Fawkes day. Effigies of Guy Fawkes are burned, among other celebrations. The word guy comes from these effigies, it was used to mean a ragtag person, like the effigies after being burned.