what is metaphor?
Metaphor is when one thing is said to be similar to another without using the words "like or "as".
John is a real pig when he eats.
A metaphor compares John to a pig without using the word "like" or "as" so it sounds like John is a pig. The reader has to determine from the context whether John is the name of a pig in the story or whether it is a person being compared to a pig. John is not literally a pig all the time. The author is saying that when John eats, he looks like a pig because he eats fast and spills food everywhere, just like a pig does.