Damn! And I thought I had it!
A Mousestroke over the grass makes it sway harder like some sort
of collision. The idea was a basic sine period of 10000. If the mouse hits
set sine period to 1000. That did the trick.
IF Sprite[Sine].Period Lower than 10000
Idea was to smoothly set the period back to 10000 but sure. From what specific Sprite?