One of the most memorable tech talks I ever attended was by a junior engineer who had just come back to the office from a major conference. Our workplace had an unusually oral culture -- decisions were made in meetings, and not always written down; there wasn't much in the way of bug tracking or work planning at the time; people generally preferred to talk through problems instead of working them out in email, chat, or forum posting.

He was supposed to present a topic he learned about at the conference. Instead, he gave a cheeky talk which introduced the very concept of written language to the audience, as if we had never heard of it. Starting from the history of writing on tablets and so on, and ending in practical advice like, "when words are written down, you don't have to remember what they were exactly; you can just read the words again." I loved the chutzpah and could barely hold myself from chortling out loudly at some of his slides.