L'amore e cieco

On the test day,
your classmate tells you he has butterflies in his stomach.
Butterflies?!
You might wonder what he is talking about.

“Butterflies in one’s stomach” is an idiom
which describes that a person is very nerves.

For example, (On the day of presentation)
I didn’t get butterflies in my stomach because I practiced so hard.

Let's try to imagine that if there is a butterfly in your stomach and it flies up and down.
You must feel suffered.
Usually, people have stomachache when they are nerves.
Therefore, by combining these two ideas above,
the meaning of “butterflies in one’s stomach” seems to be more reasonalbe.

I will have a lot of butterflies in my stomach next week because final is coming. Orz