Imagine that you have a toy box with lots of different toys in it. Some of the toys are your favorites and you like playing with them more than others. You have to decide which toy you want to play with, so you think about it and make a choice. This is what we call a rational decision.
Now, imagine that someone comes along and tells you to play with a toy that you don't like as much. You know it's not your favorite toy, but they keep telling you to play with it anyway. You might start to get frustrated and want to do something else instead. This is what we call irrational behavior.
Rational irrationality is a concept that explains why some people might choose to act irrationally. It's when someone behaves against their own best interests because they believe that their behavior will have a bigger impact on the world than it actually will.
For example, imagine that you are concerned about the environment and want to reduce your carbon footprint. You decide to walk instead of drive to work because you think that it will make a difference. However, in reality, your decision to walk instead of drive will not have a big impact on the environment. This is irrational behavior based on a rational belief.
In other words, sometimes people act against their own best interests because they believe that their actions will have a bigger impact on the world than they actually will. This is called rational irrationality.