the invluntary action of screaming at every blade of grass you see. also, a fun game to play in the car with your parents or friends.
Jeffy - "Hey Billy look, a blade of grass!"
Billy - "AHHAHHHHHHGHAHHHHHHHHAAAHHHHHHHH"
Jeffy - "Wow, you have got to get that grasscreamanitis checked out"
by Mit Romney January 23, 2008
Get the grasscreamanitis mug.