Learning to swear

Me to some of the advanced kids who came to talk to my co about something, "Do you want korean candy?" The boys laugh, "Teacher, this word and sign," as he does a slightly rude hand gesture, "it is Korean swear. It means 'fuck you' It is similar to candy name" "Oh, thanks!" "Of course teacher, ummm, don't be mad, I didn't say it to you, just teach you, ok?" "Hahaha, yeah, I know." This is the same boy who taught me that the word gossip sounds similar to the korean slang for cock. He's a gold mine!