Self annihilating sentences
Self-Annihilating Sentences, a good sized list by S. Gorn. They vary from true otherworldliness (“I am certain of it, but I may be wrong”, “You have one choice”, “I can’t stand people who look down on people who look down on people”) to Nonsense and silliness (“I’d give my right arm to be ambidextrous”, “Acupuncture is pointless”, “No one goes there any more; it’s too crowded” — unattributed on Gorn’s list, but I think Yogi Berra is supposed to have said it).
Anybody wanting to go into business in competition with Ex Cathedra can start out with a lovely pile of sigquotes. I’m a little disappointed that one of my favorites isn’t there: “How can I tell you what my opinion is until I’ve heard what I have to say on the subject?”