Related Clues:
- Taboo, to a child
- Never to be done
- Social impropriety
- Something you might get your hand slapped for doing
- Bad thing
- "Mustn't do" thing
- Talking with one's mouth full, e.g
- Texting while driving, e.g
- 4, something to be avoided
- Thing best avoided
- Talking with your mouth full, e.g
- It's unacceptable
- Not just discouraged
- Something that must not be done (informal)
- Bringing a bottle of water through security, e.g