Origin
“William Caxton, the first English printer, gave the earliest version of this saying in ‘Aesope’ (1484).
Explanation
It is said when you are frightened to do something again because you had an unpleasant experience doing it the first time. It means that someone who has been hurt or who has had something go wrong will be far more careful the next time. It’s something that you say when you have had an unpleasant experience and are going to be more careful to avoid a similar experience in the future. When something or someone has hurt you once, you tend to avoid that thing or person.An injury makes a person wary of its cause. It advises that trust, once betrayed, is not easily restored. In other words, if you’ve been hurt in the past, you may tend to become extra cautious in the future, especially under similar circumstances.
Examples
After he had left her she refused to go out with anyone else for a long time – once bitten, twice shy, I suppose.
Jill: Let’s ride the roller coaster.
Jane: No, thanks. I got really sick on one of those once—once bitten, twice shy.