Like a thief in the night simile
Used to indicate the way someone does or something happens is secretive and quick
You need to quit smoking or illness will come like a thief in the night.
She didn't want to wake the baby up, so she moved like a thief in the night.
A thing is known about by only a few people and kept hidden from others because it makes somebody feel ashamed.
To be secretly working together
A person who contributes important work to the organization but is kept secret.
To secretly punish or rebuke someone for doing something.
Do something silently, secretly.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.