Definition:

Someone who is just like everyone else; a normal person.

Example:

1) Mickey is your average Joe - he likes football, hates opera, and thinks it's a crime to do any work on weekends.

Etymology:

'Average' means 'in the middle' or 'not extreme', and 'Joe' is a common male name. So 'average Joe' refers to a man who is not extremely different from everyone else.

Synonyms:

regular guy