Hi, In several American movies you've heard expressions like "she don't know" or "she don't like.." The context is quite familiar or informal, english has many different registers. The way way English is actually used in real life isn't the manner described by most grammar books. AND this particular dialect of English that's being discussed here is called "African-American vernacular English" , also called black or AAVE in common language. It's believed that AAVE has grammatical origins in, And pronunciational characteristics in common with various West African languages. *she talkin (she is talking). *I go, they go, he go (=he goes, in standard English), she go (=she goes).

It is incorrect gramnmar, of course, but some songwriters seem to like to imitate the speech of uneducated people, perhaps to show that the words reflect the feelings of a certain class of society, like the lyrics of country and western songs. Hpwever, I really can't say. Ask a younger person.

this sentence is not correct. popular English songs tend to have a lot of grammatical errors these days. it should be "she doesn't like the lights" but with some younger people these days they may use "don't" instead of doesn't. i would not recommend using justin bieber songs for learning correct english grammar :/

Sometimes in writing poems or lyrics for songs you need to make the lines 'scan' for rhythm ... and cheat by being ungrammatical dropping out a syllable or adding one... 'doesn't' has two syllables, 'don't' has one - that's often why!

Thanks all of you. I have understood! :) It is so interesting.