During big fights in the arena or gladitorial ring between two well known or important warriors. When one looses and dies, the crowd throws copper coins into the arena for the slain warrior to take with them on their passage of death. This is to make their passage and afterlife richer and less troubled. It is a sign of respect.
Mazetown stands right around the entrance to the Maze, and its whole economy depends on the people coming to visit the ever-changing and apparently sentient dungeon. They don't get all that many visitors, but the ones that do come tend to be rather generous in their spending; after all, if anything you take inside vanishes as soon as you go in, and everyone who manages to come out usually does so with fabulous treasures in tow, why not spend your coin on R&R before getting started?