What does this line mean? 哦，您原来跟齐天大圣一个姓埃我爸差点晕倒。。
I found this on http://m.zol.com.cn/xiaohua/detail45/44743.html.
我爸是个医生。有一次，我爸给一个病人看玻那个病人问:请问您尊姓大名？我爸说:姓齐。那个病人说：哦，您原来跟齐天大圣一个姓埃我爸差点晕倒。

The real name of 齐天大圣 is 孙悟空 (one of the major characters in 西游记) so its family name is 孙, but the patient misinterpreted, he think his family name is齐.

Maybe I could translate it in EN:


  My father is a doctor. Once he met a patient.
  
  The patient: "What's your name, sir?"(very formal/serious tone)
  
  My father: "My family name is 齐(qi)" (We won't call one's first name
  if we're not familiar to him in general for regard)
  
  The patient: "Wow, your family name is the same as
  齐(qi)天(tian)大(da)圣(sheng)'s!"(surprised tone)
  
  My father nearly passed out at that time.