When one has not seen a person for some time, one can greet them with the expression "long time no see" to indicate that one hasn't seen them in a long time.
In English, it's fairly rare for such an aggressively non-grammatical idiom to stick around in common use for as long as this one has1. In doing research for this wu I ran into countless forums where ESL students were asking "Is this something that actual native speakers actually, really, seriously say?" Their questions generally had the tone of either someone who was not entirely sure if their leg was being pulled2 or someone that had been on the receiving end of the idiom unsure of whether the speaker was mocking their slightly flawed grasp of English grammar.
The actual origin of the idiom is not so much disputed as obscured. The non-grammatical nature indicates that its origin is rooted in pidgin English, but of what sort? Who knows.
In Mandarin Chinese there is an expression "好久不见" (hao3 jiu3 bu4 jian4). Broken into the individual characters, it is good or very, time, negation, and see. The story I was told when I was learning those characters was that the expression crossed into English during the construction of the transcontinental railroad, when Chinese immigrant labor routinely interacted with white laborers and overseers. Considering that I was told this by a Mandarin instructor who was also a Chinese national doesn't bolster the credibility of the story, but it's my favorite.
1: I'm not actually a linguist. I'm kinda painting with a broad brush here. Well, not just here, all over the place. What I'm getting at is that I don't own any small brushes.
2: This is an example of a perfectly grammatical idiom that might confuse a non-native speaker. When you think about all of the contexts in which you have had your leg literally pulled, I'd guess that almost none of them involve pranks or jokes.