14:48 Oct 5, 2011 

>I don't know why we say like that but I guess A ghost can never be easy! :D
Ghost is used as negative connotation as suggested by Somsak below. We never say in positive meaning e.g. เศร้ากะผี ซวยกะผี จนกะผี เหม็นกะผี ขี้เหร่กะผี (these are giving positive meanings!!)

14:18 Oct 5, 2011 

I don't think there's a direct translation (English colloquial) for ง่ายกะผี.

"ง่ายกะผี" means difficult. In my opinion, it usually is a response to something that is said to be easy but the person finds it's actually difficult. (If you think there's an expression like this in English, I'll be grateful if you let me know!)

I don't know why we say like that but I guess A ghost can never be easy! :D

11:30 Oct 5, 2011 

ไม่ง่ายขนาดนั้น Not that easy.
ไม่ง่ายเท่าที่คิด Not as easy as you thought/imagined.
ง่ายกะผี is ทนพำ colloquial e.g. easy as cake, easy as pie. ธo come up with a credible, non-cliche equivalent, is there any reason why Thai's might say "easy as ghosts"?