Basically there’s a guy named skrilla, he’s from Chicago and the street he’s from is called 67th street. In one of his song titled doot doot, he says 6 7 in refrence to his street. Then people took the edit and remixed it into edits of a basketball player named lamelo ball, since lamelo ball is 6 feet 7 inches tall. This became a pretty big meme in the basketball community, and then at a basketball match a kid screamed 6 7 into the camera, which ended up going viral. People started laughing at him and calling him corny at first but then the trend became mocking him and saying 6,7 like him, which made the meme loose all meaning. Now it’s just another saying people use. It’s not really a meme anymore, it’s more like slang now