nananaitis
When you only know the famous part of the lyrics to a song and forget the rest. Symptoms include singing the first few lines enthusiastically, and then mumbling, humming, and stuttering during the rest of the song. People like this should either do some research or keep their mouth shut.
nananaitis victims

1: You're lipstick stains!...ehnanananana left side brains! dadadada wouldn't forget you!

2: When I was thirteen, I had my first love...jflsfn lnnfanlksksckmksmldsmfjlsnnvkslfsjlkxjvmekfmilfsaln above.

3: Hi, my name is! My name is! My name is! Slim Shady! Hi kids do you like violence? eh duh umm eh uh EYELIDS! wanna cough on me and do extract um erh.................did? try uh um er and get messed up life is? My brain's dead weight, trying blahblahblahblah but I'm ..uh bluhhhh PREGNATE!

4: Blah blah blah blah blah blah blah
Comin out your mouth with your blah blah blah

Oh wait, that's right...