Lose one's marbles

1981 April 13, New York magazine, vol. 14, no. 15, There it was again, the suggestion that the governor had lost his marbles. And, to be truthful, Breslin is a bit late on the loony angle.

If my golfing friends would see me now, they'd crap in their pants laughing at me. They'd say that poor jerk had lost his marbles.

Jimi's obsession with his guitar garnered him a nickname around Clarksville: Marbles. He was so named because people thought he had "lost his marbles" and was crazy as a result of his excessive practicing.

On the substance of Smith’s grumble – that Microsoft’s remedies for the cloud part of the gaming market were sufficient – opinion obviously differs, but the CMA hasn’t lost its marbles.