It means a dirty joke : “69” is a sexual position, and “mouthwash” is the punchline because it plays on the idea of needing to rinse afterward.

What people mean by it

  • The joke usually implies oral sex, since “69” is slang for that position.
  • “Mouthwash” is the humorous follow-up because it suggests cleaning your mouth after it.
  • Online, people often repeat it as a simple one-liner: “What comes after 69? Mouthwash.”

Why it’s popular

  • It’s short, easy to remember, and works as a teasing punchline in casual conversation.
  • The joke has circulated for years across forums and joke sites, so it’s become a familiar internet gag.

In plain English

If someone says “what comes after 69 mouthwash joke,” they’re usually asking what the joke means, not asking about a real sequence. The answer is just a sexual pun, not a literal fact.

TL;DR: “Mouthwash” is the punchline to a crude joke about the sexual position “69”.