I gotta feeling

Now I'm listening to Black Eyed Peas' song "I gotta feeling" over and over again from YouTube. It is recently No.1 song on the Billboard chart USA and often played on a radio, but I don't quite get it's lyrics. To make sure it, I'm watching the video with lyrics from YouTube and also humming quietly(because of midnight). I'm wondering, if native English speakers listen to this song just one time, do they can understand exact meaning and what the lyrics is?. For my case, I can almost understand whole contents of Japanese music (However, recent Japanese music's lyrics tend to be complicated and hard to be understood)

Once I read it's words, it is actually easier than I thought. OK, I'm gonna try to remember the all lyrics, and someday I wanna sing this at a Karaoke bar. Now I gotta feeling that singing a English song is gonna be fun!