wet grass
Grass that has had precipitation land on it. Also known as a silly goose.
You better get off my yard, it contains wet grass because there was a tsunami last night.
cool wet grass
An expression of difficulty. This will often be said repeatedly while doing something difficult that you have to do and want to get finished. It originated in amateur firewalking as a way to create a mental image that no, your feet are not burning.
Joe ran through the bullet-riddled alley, muttering "cool wet grass cool wet grass cool wet grass" under his breat