Term you use when some one does something, in the world of extreme sports, that you could easily do. It's a figure of speech meaning you could do the same thing switch, riding or spinning the opposite way you normaly do, and naked, taking, away the security of clothing, hence if you fell you would be naked and scrape your behind. Sometimes it good to actually do things switch-naked.

When you eat dirt for the first time and leave your family to build a shack in the woods