Definitely check out the link from the first answer to see what the speaker meant. I'm only chiming in with a cultural note: "nigger" is considered a highly offensive racial epithet in America. Even people who don't blink at foul language will say "the N-word." It's sometimes used in urban street slang and rap music, but never in polite conversation. Good luck with your studies!

Yeah, it basically means "to slobber" (all over something). The expression is probably going to be offensive to most people, and highly offensive to some people. Anything with the "n- word" in it is not politically correct to say. And the word does contain heavily racist overtones, even if that is not what you mean. I would say "slobber" instead, like slobber all over the cigarette, if you are talking about a cigarette. In America, at least, even words that /sound like/ the n- word, such as "niggard,' are offensive to some people, even though the etymology is completely different.

Urbandictionary seems to have 2 meaning. Check them out, here: http://www.urbandictionary.com/define.php?term=nigger+lip