What does my good friend mean when he says I'm a rotten egg?

"rotten egg" is usually a swearing word, which means that someone is bad and unpleasant. This statement is usually insulting, probably because eggs are usually fresh food, and if they go bad, they will give off an unpleasant smell. So people use the word "rotten egg" to describe some people's behavior or personality similar to rotten egg, which makes people feel disgusted.

If your good friend calls you "rotten egg", it may be that he/she is dissatisfied with your behavior or attitude, or is joking and teasing you.

However, this statement is usually insulting, and it is recommended not to use it at ordinary times, so as not to cause unnecessary misunderstandings or contradictions.