It is a behavior towards things, which show self centric approach , thinking that other people are less important then he is. An ill organized behavior which shows selfishness, even not knowing with what is next for to do...
It happened while we wait in a queue,waiting for bus, or things like that.
But in case of CSS or any exam we generally become impatience because, we want to move towards our next task. so we can figure out lope holes, mischiefs and how to rectify it an how to improve it become.
In general we already know what to do next, a plane in mind, through result we want to measure our self, our capabilities , a well defined attitude make us impatiens.