Jancok, also spelled jancuk, is a well known swear word from East Java, Indonesia, especially associated with Surabaya slang. Offline it can be an insult, a cry of frustration, or even friendly banter depending on tone. Online the shouted version spread through Indonesian gaming clips, chat audios and short video edits, where it became a reusable reaction alongside other short shouts like bruh. Its blunt sound and local familiarity keep it popular for moments of shock and comic anger.