When you remember an embarrassing moment in your life that you caused and you either cringe, hit yourself in the face or flail your arms because of it.
Dan: Yeah cool. *cringe attack*
Phil: Are you okay Dan?
Dan: .... *still flailing arms*
Phil: Oh your having a cringe attack.
When your lying in bed at 2:00 am and you remember that one embarrassing thing you did three years ago. And you start to cry because it made you cringe so much.