flat

if someone says you are flat, it means ur flat basically.
oinkawa dooru is a very well represented demonstration of this term referring to his FLAT ASS

guy 1; "ayO lOokiE hErE, ShE flat aSfFFFFf"
guy 2; "nah nah she built like a door deadass"
guy 3; " but she do be flat like thattttttt"