A word to take the place of any other word or phrase when you can't say the original word/phrase for any reason. ( Too nervous, agaisnt the rules to say it, forgot what you were going to say, ect.)
Guy: Hey.. I just um... wanted to tell you somthing...
Guy: Uhmm.... uhhh... Jabbawabba... (Oh man I'm so lame...)
Girl:Really?! Me too!
Guy: What? You know about Jabbawabba?
Girl: Duh! Everyone uses Urban Dictionary!