When a delusional yukkuri(s) finds out (or is about to find out) that reality is not as wonderful as they biased delusions. Sometimes it can lead to throwing a tantrum, despair or even anti-yukkuritis
A common example is an unborn/newlyborn koyukkuri believing that they're destined to live a life full of easiness as a pampered pet yukkuri only to be born into a modest or poor wild yukkuri family.
Another common example is a shithead yukkuri believing that they're strong enough to take on a human only to be defeated and abused.