我的神啊 (wǒ de shén a)
Where does it originate?
“我的神啊”(wǒ de shén a) first became popular from a hot Chinese TV series武林外传(wǒ lín wài zhuàn "My Own Swordsman")as a pet phrase of Tong Xiangyu, the owner of Tongfu tavern. Then it has been widely spread on the internet. Actually,“我的神啊”(wǒ de shén a) is the assonance of Shaanxi dialect 额滴神啊(é dī shén a).
Where is it used?
Because of its dialect-originated feature, “我的神啊”(wǒ de shén a) is usually used in informal circumstances and among familiar people. You may not say it to someone whom you have never met before or who has a higher rank than you. It is impolite.
Examples:
Someone eventually gets an offer after a long time of job-hunting, she may say:
我的神啊，终于找到工作了。(表示激动)
w? de shén a, zhōng yú zh?o dào gōng zuò le. (biǎo shì jī dòng)
Oh, God, I finally get an offer. (express excitement)
A man and a woman got married, but people around them never thought it would happen.
They may say:
我的神啊，他们结婚了!(表示惊讶)
w? de shén a, tā men jié hūn le! (biǎoshì jīng yà)
My god, they got married! (express astonishment)
From: www.raychinese.com