Phrases on secrets:
1. Keep it under wraps.
2. My lips are sealed
3. Don't spill the beans
4. Don't let the cat out of the bag
5. Behind closed doors
6. Give the game away
7. Keep it under your hat
8. Mum's the word
9. On the quiet
10. In strict confidence
11. Be as quiet as a mouse
12. On the sly
13. Don't dish the dirt
14. Take the lid off
15. To be a dark horse
16. Off the record
17. Poker face
18. To bite/hold your tongue