1. This secret agent.
2. This master of disguise.
3. This curious investigator.
4. This tricky operative.
5. This nosy neighbor.
6. This covert peeker.
7. This devious double agent.
8. This duplicitous mole.
9. This shifty observer.
10. This undercover agent.
11. This deceitful snoop.
12. This sly infiltrator.
13. This underhanded watcher.
14. This sneaking scout.
15. This surreptitious lookout.
16. This stealthy spy.
17. This slippery sleuth.
18. And this very deadly assassin.
