Some advice for time travellers from The Big Jewel:
* Watch out for a caveman named Zog. His father discovered the magic of fire. Zog discovered the magic of gouging people’s eyes out with a sharp rock.
* Be sure to check out the natural beauty of North America back before the arrival of the white man: virgin forests, unpolluted lakes and rivers, and, echoing across the plains, the thunder of stampeding unicorns.
(Thanks to Edward Arthur Ling Page for the link.)