Good egg

A good, kind, and well-intentioned person

Some people are simply decent human beings. They may not be extraordinary,but they are also not bad people. These people are good eggs. They have good intentions, and they are kind to others. They do their best and try to be dependable.

A good egg is a person who has good intentions. 

Idioms like this one often have logical opposites. For example, a “warm-hearted” person is very kind and friendly, but a “cold-hearted” person is very mean and unfriendly.

When someone is a “good egg,” they are trustworthy. You can ask them to do a favor. If they say yes, you can trust them. They will do the favor. You can be confident about this because you know this person is a good egg.