Krutoi Sem is the Russian title for Serious Sam, the fast paced first person shooter series created by Croteam and first released in 2001. The phrase zdravstvuy derevo, literally hello tree, comes from the Russian voiced version and caught on with Russian speaking players as an ironic greeting. Derevo can also imply someone is being dense or unresponsive, which helped the line spread beyond gameplay into chats, streams and short meme edits where a dry hello to a wooden person or object is the whole joke.