I once read that you could take the most articulate, eloquent intelligent statement, phrase or sentence and by simply adding the words "and stuff" to the end of it, sound like a moron - it's true
The use of the word "like" as discussed above (great article, by the way, but most young people could have probably already told you that), although I do hate it when people use it instead of "says" - "she was like, yeah let's go!". I thought this was generally something only used by people younger than me (I'm 30), but I was watching an old documentary from the 60's, and noticed one person use "like" instead of "says" several times! Guess it's nothing new.