Gymnastics but the two bars randomly pop out razor blades and the ground below is a blender

Archery/shooting its 1v1 but the target has a button on it that slams a spit through the loser

Boxing is just boxing but with brass knuckles and no clothes

Cycling but the road slowly falls out behind the cyclists

Diving all water except a small circle has been replaced with concrete

Rowing there is a hole in the boat and the water is filled with rabid Piranhas

Longjump/double jump/ triple jump the floor before a certain point has been replaced with a deep fryer and it gets extended to the landing point of whoever makes it

All the running sports a bunch of traps on the track like saws and pitfalls and arrows

Pole Vault/high jump replace the bar with razor wire

Javelin/shot/hammer/discus human targets on the field