Grand Clong

That awful feeling when you realize you have just said something horrible, or you are supposed to be somewhere you aren't, or have forgotten to bring/do/say something important. Cartoonist B. Kliban coined this term and defined it as 'a sudden rush of shit to the heart.'

She experienced a Grand Clong because she had just asked an acquaintance how the kids were, before remembering they had both died recently in a car wreck.

He received a text asking where he was, and immediately suffered a Grand Clong when he realized he was supposed to be at the Very Important Meeting instead of at a matinee movie showing.

Standing at the podium in front of the packed auditorium, a Grand Clong washed over her as she pulled her folded speech printout from her pocket and saw that it was her travel itinerary.