"Unwritten rules" become established naturally in sports over time. They're not officially in the rulebook (hence "unwritten") but they're guidelines that are acknowledged and followed by most around the sport regardless. 

Some of them are fine and serve a noble purpose, but far too many are lame and estabish more limitations than are needed. 

So, what's the very worst one from each major sport? Let's examine.

By Pete Blackburn