Why Do We Shout In Anger?

Another point to consider: we yell in anger only to those we are close to. If the anger-triggering agent is a person we don't know or care much about then we may try and express ourselves or we may try to rectify the situation, but we almost never will yell at strangers.

Also, maybe that anger builds up?

 This past weekend, I took my mother in law shopping.  (She needed a new frying pan . . . among other things.)  
When she came across the pan that came with a glass cover, she was sold!  I pointed out the "small port" in the the lid built in to release excess pressure r/t the heating process.  
There is only so much space in a body/mind/spirit for frustration to build up.  Like my mom in law's new pan, we need to have a port from which, we can safely and effectively get rid of "the stuff we cannot by nature hold".  
Without a built in/controlled method to "expel" excess . . . , we boil over.
Always love 

 excellent analogy.  Pranayama is excellent for that very situation.
Pratibha G

 for sure anger builds up. anyone can see that.  reflection on a situation without selfish intent can lead to discriminative thinking about a situation, and this can regulate type of appropriate response.