I'll admit that I read all of Confederacy of Dunces before looking this up. Ignatious often referred to his pyloric valve closing or having serious problems whenever he was stressed (and that was often). I figured it had something to do with his stomach or having gas build up.
Here is a definition I found:
The pyloric sphincter, or valve, is a strong ring of smooth muscle at the end of the pyloric canal which lets food pass from the stomach to the duodenum. It receives sympathetic innervation from the celiac ganglion.
He used this condition on par with Fred Sanford clutching his chest and yelling for Elisabeth. One of the things I liked about this book is how others reacted to this fool, which was basically not to challenge him (except maybe for his mother). This cast of characters truly fit the title.
I doubt if I'll ever use this conversation, but I'll certainly remember if I hear someone on Grey's Anatomy say it (if I ever watch it, I mean). And if anyone reads this and then reads one of my future novels that has pyloric in it, then you will certainly get the private joke and tribute to Ignatious.