What kind of act is it????!!!

Yesterday was standing inside the train when I saw a primary school kid spit something out of his mouth...looks like brownish grass...and then throw them into his bag...Ekkksss after I saw this act I wanna vomit out lol...Dun have the slightest idea why does he needs those spitted grass for wat and worse still throw them inside his bad...So dirty hahaha...Maybe I old liao that's why I dunno what those youngsters are thinking about...Feel like taking a pic of him spitting out but in the end didn't...scare that I will crush his minute glass heart....