When someone's head is concaved inwards like a
brainlet or as if you dont have a brain. Used to
diss someone for being a
retard or as a threat.
"Yo Jimmy, you know that
Nick guy? He's so fkn concave"
"
Nick, watch your mouth or I will make you concave"
"Pass me the cheeky Nandos or I will concave your head"