I am watching The Expanse tv series and have encountered the following dialogue:
- I need to borrow your spy on Tycho Station.
- What for?
- To keep an eye on Fred Johnson. He's over-charging the Mormons for their toilet seats.
- Well, you can't have him.
- Why not?
- It took me five years to sheep-dip him in Johnson's outfit, to steal tech for his competitors.
What does the verb to sheep-dip mean in the context?