It's over 9000! is a popular internet meme originating from the popular anime "Dragon Ball Z".
In the original Japanese version, Vegeta's line was "It's over 9000!". This was changed in the dub to match Vegeta's lip movement during this bit of dialogue. The translation was actually wrong and vegeta said it's over 8000 in the original! Over 9000 was only referenced in a badge for teh meme wiki users..
The line has been used in various forms of media, to show when there is a large amount of something or it could just be used for fun.
Use in Popular Culture
In the visual novel game "Phoenix Wright: Ace Attorney", the character Sal Manella uses the phrase.