Create a map based on a competitive sporting activity. I'm willing to define 'sport' pretty loosely, but it should be an organised event, the kind of thing that people come to watch, with some sort of prize or distinction awarded at the end.
The 'sport' can be real life, or fantasy. It can be anything from an Olympic sport to something you made up, so long as it's clear what's happening. You can map the route or venue of the event, show where spectators gather, include some detail on the sport (perhaps basic rules, info on the contestants, what prize is awarded etc etc).
Examples...
A race of some kind (car, bike, marathon, swimming, boat, interstellar)
A stadium or arena event (ball games, horse/chariot racing, gladiator fights)
An alpine sport in a snowy mountain resort
A golf course, jousting tournament, or a kids' Egg & Spoon race down your local park
An Elvish archery event, a Dwarven axe-throwing competition (or maybe a drinking contest in a mead hall), or a game of Quidditch
Other rather more esoteric examples would be the running of the bulls in Pamplona, Extreme Ironing (I would, quite frankly, love to see this!) or England's greatest ever sporting event: The Cheese Roll.
It's pretty wide open to interpretation and I think we could see a good variety of maps.