Change one thing about a sport to make it absurdly dangerous.

[Grach]

Volleyball: The ball is a nest of yellowjacket wasps.
Tennis: The rackets get replaced by pistols.
Polo: The horses get replaced by angry tigers.
American Football: The ball gets replaced by a giant vial of nitroglycerin.
Poker: The cards are made of sharpened obsidian.
Chess: Each piece is a person and whenever you take a piece they get knocked out.
Football: The field has nails instead of grass.

 

[DRTJR]

Soccer: Each player has a Battle Royal style collar and each time you score one of the members of the opposing team's collars will go off, play to the last man standing.

Magic the Gathering: For each hit point lost 1/20th of the oxygen is removed from the room are in.(Both players are in separate rooms.

 

[Zeren]

Soccer: One randomly placed and expertly covered 2 foot wide hole that has a bear trap in it. Place bets on who steps in it and when.

 

[The]

Baseball: Spiked bat

Soccer: Ball explodes if not kicked for 30 seconds.

 

[TotalerKrieger]

Hockey: plastic stick blades become razor sharp sickles. Protective gear is prohibited. Fighting and blind-side hits to the head are encouraged.

 

[funkyjiveturkey]

i say put landmines in the outfield in baseball. it'll certainly liven it up a tick

 

[Phrozenflame500]

Golf: Upon losing a tournament you must sleep with somebody else's wife, and then have that guy find out via national television

Hockey: No change but there is no protective equipment allowed

League of Legends (that's a sport now right?): After playing a game, you must joke around on Facebook until the US Department of Homeland Security gets mad and puts you in jail

Soccer: Replace the players with Soccer Fans

Wrestling: Tell the producers they will get higher ratings if they can work the players killing one another in their script

 

[Kal-Adam]

Tennis...

But first you cut off all of the players arms and legs...

Am I doing it right?

 

[Lilani]

Since it's now officially a sport:

The amount of pain a LoL character is going through is simulated onto the player through electric shocks.

 

[Johnny Novgorod]

Inject nitroglicerine into baseball bats so that players will have to balance their swing so that it's strong to knock the ball pretty far away but not strong enough to blow themselves up.

 

[Izanagi009_v1legacy]

I choose American football. Velociraptors on the field.

How about replace the Football with a Mini Nuclear bomb and that if the game goes into overtime, It explodes

gives a whole new meaning to the "nuclear football"

 

[rednose1]

Baseball.
Replace ball with grenade. No one will be going for those foul grenades any time soon.

Plus, it makes the pay seem more worth it.
"I can't believe [Player Name] is getting 30 mil a year!"
"Yea, it's kinda high, but he DOES have to catch live grenades for a living."

 

[Izanagi009_v1legacy]

Formula one where the tyres at deliberately designed to explode during the race....oh wait that ones already been done

Golf where the golf course is littered with alligators...weve got that one too

How about we take MMA/cage fighting and we add lions and instead of a cage we have a massive outdoor arena and we give them random weapons too....weve had that one too but it was a while ago perhaps its time to re-introduce it

How about have MMA/Cage fighters augmented with weapons like in Tokyo Gore Police and advanced sub-dermal armor to prolong the fights . When a fighter is hit too many times or is pinned, He can literally swap his flesh and blood for any melee weapon (sorry, folks, no guns): chainsaws, high frequency blades, hammers, sawblades, and jackhammers. The winner is the one who beat the opponent into submission or death first

 

[Demolition_Human]

Nascar: You know the movie Death Race right....with Jason Statham? Yeah pretty much that except its now 500 laps of explosions, gunfire and rockets or until someone is left driving.

 

[Izanagi009_v1legacy]

Hurdling - all hurdles have spinning blades attached.

how about having them be randomly change height and have laser cutters on them. One moment you clear it the next, you have a leg cut off

Sprinting - instead of a starting gun the competitors instead have to outrun the gun.

or have them out run a ball and chain being fired at them with the ball replaced with explosives and the chain be super heated (sounds like the thing in Bulletstorm)

Relay - the baton is on fire

or have it be a semi-frozen cobra, if you don't get to the end on time, it bites and kills you

Bull Fighting - Replace the bull with a tiger

or better yet, mecha tigers with plasma sheathed teeth and a chainsaw on the tail

 

[Gunner 51]

Tennis: Cut down long boring matches by replacing the ball with a hand grenade.
Football: Remove the referee and watch the chaos. (Just like when it first started.)
Rugby: Give players spiked shoulder pads.
Snooker: One of the pockets is rigged with explosives. the players don't know which one.
Motor Racing: Replace F1 cars with stock cars with on board machine guns.

 

[Spartan448]

Griffball.

It's a sport where you murder people with swords and hammers and score by planting a bomb at the other team's goal. How do you make that more dangerous?

*Tank cannon heard in background*

You give the spectators tanks.

 

[Izanagi009_v1legacy]

Nascar: You know the movie Death Race right....with Jason Statham? Yeah pretty much that except its now 500 laps of explosions, gunfire and rockets or until someone is left driving.

In Death Valley, with spectators able to launch bombs and rockets at a whim, and the wall is coated in lasers, and no pit crew

 

[PJGlenn]

Any swimming sport, any at all; just add sharks. Curling; replace the rocks with any volatile explosive, same with shuffleboard. Golf add crocodiles. Football(American); just add spikes to everything, including the ball. Soccer(football); add landmines. Hockey; make the blade of the sticks a real blade, a la total recall. Baseball; replace all balls with live grenades. Basketball; raise all the baskets to the roof and replace the floor of the court with one giant trampoline.