There is at least one quote in each Critical Reasoning lecture materials. Some are funny, some serious. I looked through all of them and these are the top10 (not ranked) that I found interesting:

1. Some people are constructive, if you like. Others are destructive. It's this diversity in humankind that results in some making positive contributions and some negative contributions. It's necessary to have enough who make positive contributions to overcome the problems of each age.
—Jonas Salk

2. Dinosaurs didn’t study critical reasoning. Now they are extinct.

3. Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing 'look over there'.             
—Randall Munroe

4. Advertising is legalized lying.             
—H. G. Wells

5. If you make the same guess often enough it ceases to be a guess and becomes a Scientific Fact. This is the inductive method.
—Bertrand Russel

6. I may as well say at once that I do not distinguish between inference and deduction. What is called induction appears to me to be either disguised deduction or a mere method of making plausible guesses
—Sherlock Holmes

7. Once, in a lecture at Columbia University, eminent Oxford philosopher J.L. Austin explained how many languages employ the double negative to indicate a positive (“he is not unlike his sister”), but that no language employs a double positive to make a negative.

Columbia professor Sidney Morgenbesser, sitting in the audience, waved his arm dismissively, and retorted: "Yeah, yeah."

8. When a diplomat says yes, he means ‘perhaps’;
When he says perhaps, he means ‘no’;
When he says no, he is not a diplomat.
—Charles Maurice de Talleyrand

9. Time flies like an arrow, but fruit flies like a banana.

10. After all we speak of people ‘taking refuge’ in vagueness—the more precise you are, in general the more likely you are to be wrong, whereas you stand a good chance of not being wrong if you make it vague enough.
—J.L.Austin