Once, when I was walking on a sidewalk, I saw a teen couple about the age of eighteen walking down the road. I passed them and said "Hello!", but they didn't reply. About four weeks later, I saw the same couple and greeted them with a "Hello" again. This time, they replied saying "Hi, Sweetie!" After about a month, I read an article about two teenagers who were beaten to death at a local barber shop. Pictured in the article was the couple I met on the sidewalk. At about 9:30PM, I got a mail in the letterbox with no contact information. I opened the letter and it said "Hi, Sweetie!" 
Удачи!... ;)