When your cover is
blown; To be exposed of; Found out about; To get
caught.
Specifically applies to that of criminals, spies, moles, undercover
police, etc.
Kathy and Jonathan found their front
door open as they returned home from a movie. Apprehensive, they walked inside only to see a burglar slipping out the back window saying, "I've been made"!
Kimberly was caught stealing
cookies from the cookie jar at grandma's. She's been made.