Long time, no see


Used to get this message from chinese chat friends when I used to meet them online after a period .. A first glance made me think that the phrase is not correct grammatically and even said so to them. One of the them even defended her stand but I wasn't sure if it was correct.

I was watching 'Spiderman' for 3 time and heard this phrase when mary meets Peter Parker after a couple of weeks and says this 'Hi peter, long time, no see'