When the weeds rank of dank makes you that way. The name comes from the above the influence commercial called "flat".
Other symptoms of being flat include being anti-social
2) What one might call a girl's chest if she has a little cup size or no boobs at all.
3) A word that is not veiwed as offensive or foul, but can be substituted for any words that are offensive or foul.
2) Drew: Dude, Amy is so flat.
Nick: She's only three years old...
3) Paul: Flat! What the flat is going on here?!
Marie: Just shut the flat up! You would never flatting understand anyway!
Joe: Flat you marie! You flatting flat! I never want to flatting see your flatting face ever flatting again!
Paul: You're such a flat...