I vote for masturbation to be the most dangerous sport actually.
Reasons its a sport.
1. It gives you exercise and makes your stronger.
2. It releases stress and pressure.
3. It is done by everybody at some point in their lives, some more often then others.
Reasons its dangerous.
1. Too much of it can cause pain or over excitement.
2. If you get caught you get more pain.
3. If not done properly can cause 'stains' on clothes or a mess on the carpet.
This was a serious post just so everybody is aware.