This prompt was inspired by a Public Service Announcement from the fabulous HanaLena Fennel regarding the statements followed by the word “but”:  “‘If you start your statement with ‘I'm not defending the guy, but’, you are 100% defending the guy.” Corollaries to this are the “I’m sorry, but...” (no, you are not, as also noted by HanaLena) and “I’m not racist (sexist/homophobic/bigoted/asshatted), but...” (yes, you are, as pointed out by numerous people). 

The prompt is to begin with one of these statements and make it obviously false: “I am not a dinosaur, but I lived during the Mezoic Era, I am nicknamed pterodactyl by the unsophisticated, my best friend was a Pterodactylus, and the paleontologist Othniel C. Marsh once told me I had good bones.”

Reverse prompt challenge: take a statement in which the information before the “but” is equally valid other than “I like scrambled eggs, but I prefer donuts” or similar food/drink/pet/music/sex or other type of preferences. Please message me when/if you do!

Not really an example of the prompt, but I just like the line (and title and poem) so much: “Not Waving but Drowning” by Stevie Smith.