The act or process of going crazy, usually caused by life stressors. Also used in the past tense phrase: lost my marbles. The orgin of the phrase is unknown but has been referenced numerous times in popular culuture; such as in the peter pan film Hook from the 90’s.
I am losing my marbles staying locked up in this jail cell.
Jimmy spent his entire summer indoors studying and ended up failing his medical boards, he has since then lost his marbles and is living under a bridge.