This piece folklore is actually a running joke in my family. I have heard it dozens of times ever since I was a child. My family has a Serbian heritage that we are very proud of. When I told my mom I was collecting folklore she insisted I include it.
“A man goes to visit his best friend. The friend’s wife comes to the door. She says, “I am sorry but your friend is very sick.” The man says, “Give him this green tea it is very good it will make him sweat,” the next day the man comes back to his friends house and knocks on the door. The friends wife comes out. She says, “I’m sorry to say but your friend died in the night,” “but did he drink the green tea,” the friend asks? “yes,” “and did he sweat,” “yes,” she says. “Very good” says the man “it is good that he sweats.””
Final thoughts: I think this joke say a lot about Serbian humor and Serbian culture in general. Most Serbian jokes I have heard fall into the genre of black comedy. Serbian sayings also tend to be very pessimistic. I think this comes from the fact that Serbia has an incredibly violent and tumultuous history in the last hundred or so years. Multiple genocides as well as an incredibly destructive civil war has led Serbians to focus on more morbid humor. When you have to deal with death on a regular basis you have to find a way to laugh at it and this is what these types of Serbian jokes allow people to do.