That butterfly feeling

Semau diawali sebuah pertanyaan tentang "butterfly feeling" di sini saya jadi kepikiran

have you ever felt that tingling sensation inside your stomach?

some say it's like having butterflies in your stomach.

that's probably why she referred to it as "butterfly feeling"

cananybody tell me how it happens? what triggers it?

i did some googling and found this

http://en.wikipedia.org/wiki/Butterflies_in_the_stomach

but i would really appreciate some personal accounts on this.