Everyone has something about themselves that they would like to change. Some part of their personality that isn't purely pleasing to them. For Cordle in "Cordle to Onion to Carrot" by Robert Sheckley, it is the fact that he has been bullied most of his life. He explains that it's not the type of bullying you see in the atlas advertisements where a bully kicks sand on you, but Cordle has a push to change. He is given a drug that gives him the chance to be something different.
While he is high on this drug he has numerous epiphany but the only one he remembers is a discussion about onions and carrots that basically goes that the world is full of different types of people, some are onions and others are carrots. Both are perfectly reasonable but you have to be one or the other. Something about the drugs or perhaps just the need to change allows him to change his personality. He decides he no longer wants to be an Onion who is pushed around but a Carrot.
Much of the story takes place after this change in personality as Cordle does the things that we have always wanted to do. He begins by going to a French restaurant and when the waiter is rude he make a huge scene, becoming the bully instead of being the one who is bullied. He holds nothing back and in the end it works. The waiter brings him the meal he asked for, but rather than eat it Cordle dumps the food out on the floor and walks out.
He continues this pattern for some time refusing to be bullied but instead becoming the bully and he is considerably happier, remaining the same person he has always been most of the time but changing completely when bullied.
Then he meets a woman. She likes him, but when they attempt to go into a club that requires a necktie and coat Cordle attempts to use the same tactics he has with others. He takes her coat and puts it on, then ties a dirty handkerchief around his neck, and when the man says it isn't right he threatens him with a defamation suit. The problem is that she doesn’t appreciate the way he acts as much as he dose and he is forced to promise to not act this way any longer.
There is a great deal going on in this story. The idea of changing who you are is one theme, but there is also the question of bullies as well as the effect that women have on men. All of this combines into a story that could have been a simple stress relief for a tried writer but became something more and it is that something more that makes this short story worth reading.