1) To take a picture of someone/something without looking through the viewfinder; usually done on the sly.

2) To secretly take a photo of the unsuspecting in a sneaky manner.

3) A method of photography developed by the Yarn Harlot

To surreptitiously photograph a celebrity or person of interest because you are too nervous or respectful of their privacy to ask for a photo

coined by The Yarn Harlot