look up any word, like fluffer:
 
1.
a substitute phrase for 'are you serious?', whch can be modified in a number of ways, eg 'are you for cereal?' (are you for real?)
Johnny: I just saw Britney Spears walking down the street
Kate: Are you cereal?
by katattack November 13, 2007
 
2.
Used to be what the cool kids said in school, but then the nerds took it over. Meaning: Are you serious??
Cool kid: eh mah gawd I saw an adorable guy yesterday in the hall way!!

Nerd: Are you cereal??!

Cool Kid: Don't try to be cool, k?
by Bailsmh January 08, 2009