Phrase that means take your anger out on your own. Don't hand it (your anger) off onto someone else because you'll only be ruining someone else's day. To take someone's anger out on someone undeserving of it.
The story is: The boss learned that her company lost a client and so angrily fires an employee. The employee has a family of three and a wife to feed. He gets home
disappointed, upset, and angered and so yells at his wife because the steak was a little raw. The wife after slaving at the stove for hours becomes pissed. She shouts at her eldest to stop trying to break his neck and do something with his life other than skateboard. The eldest, a regional-winning
skateboarder becomes angry and on his way to his room, pushes past his
younger brother saying "
Watch it buddy, I'm not in the mood." The younger brother, who loves his older brother & practices everyday on his skateboard to be like him, becomes so uncontrollably irate that he goes back into his room, sees his cat sitting on the bed and kicks him.
The point is: You can't control whats going to happen in a day. It's best to think it over for another day. And to save a lot of people a lot of weariness and hard feelings, kick your own damn cat!