Edward Tufte, author of The Visual Display of Quantitative Information, was willing to speak to the Skeptics Society at Caltech in return for an unusual honorarium: the opportunity to see Feynman’s van. From The Feynman-Tufte Principle — A visual display of data should be simple enough to fit on the side of a van:
Richard Feynman, the late Caltech physicist, is famous for working on the atomic bomb, winning a Nobel Prize in Physics, cracking safes, playing drums and driving a 1975 Dodge Maxivan adorned with squiggly lines on the side panels. Most people who saw it gazed in puzzlement, but once in a while someone would ask the driver why he had Feynman diagrams all over his van, only to be told, ‘Because I’m Richard Feynman!’