Is inhaling grass bad?

I am starting to do something dumb. My friend introduced it to me, and I was wondering if it is bad. He gets a bunch of Zoysia Grass, puts it in a leaf, then inhales it so much that it goes up there nose. I tried it, and it gave me a headache, even if it didn't go up my nose. So I was wondering if this is bad. I didn't smoke it.

If the grass has been fertilized recently it could be very dangerous.

What you're experiencing is the power of peer pressure. You realize it's 'dumb' but because your friend is doing it, you do it also. You are a lot brighter than your friend if you realize it's dumb. Why don't you do the thinking and help him find something more productive to do than that?