Top definition
An offensive manuever done by bending over and placing your head between your legs. Then take your middle finger and put it right in front of your ass, and fart. Your finger will resemble a blade of grass as it blows through the wind.
He really must have been pissed, because he totally gave that guy the grass whistle.
by th3_duk3 September 08, 2009
Get the mug
Get a Grass Whistle mug for your daughter-in-law Beatrix.