7 - 8 - 9 - 10 pin leave
I only ever saw this once and it was about a year ago at Highpoint Bowl. The girl who left it would have been about six years old and she was in a bowling birthday party.
I saw the leave from the corner of my eye as I was leaving. I stood around to see the next shot.
She bowled the ball and it hit the middle of the #7 & 8 pins which the 8 pin then hit the 9 pin, and the 9 pin hit the 10 pin for a spare.
I'm sure she may never know what she really achieved.