I love sports. I played a lot of them as a kid and during my (short) time in college. One thing that has always been generally missing from D&D cultures is sports. Sure, there's the odd Quidditch match or old-school Gladiatorial Combat Episode, but generally, that level of cultural detail is left in the hands of DMs.
We can easily find inspiration for fantasy sports in the games we play in the real world. Here are a few examples.
Ice Hockey is my favorite sport, and one I played for as long as I can remember. It would be unlikely to find this sport in temperate climates, but in places that have snow for a large part of the year, and lakes that freeze, it would be possible. I can envision a large gathering of frost giants that gather annually on a big frozen lake for a hockey game. It would be a rather frightening event for the local villages around the lake, especially if there was regular collateral damage from errant pucks or body-checks!
Soccer is a simple enough game to learn and play; there's a reason it is the most popular sport in our world, largely because all you need is a goal and a ball. Balls could be made from monstrous hides, which could impart some interesting side effects. A World Cup-like event would draw thousands of people from across the continent, depending on the ease of transportation in your fantasy world, including heads of state and other powerful and wealthy individuals.
Lacrosse is a sport I was never overly fond of, so I envision it as something goblins would play, possibly with spikes adorning their nets. The PCs could get captured and forced to play a possibly deadly game against the goblins.