When in conversation, person A says something that person B knows is sarcastic but cannot detect the
sarcasm in person A's voice. Derives from when a
grasshopper is in the
grass and you know it is there but you cannot see it.
After Steve has had a mild day of
work/school mainly consisting of fooling around.
Steve: "Today was really tiring, I had loads to do"
Alan: "Really? Or is that just grasshopper
sarcasm?"