There's a massive fat guy in the local area here who goes blasting around the place on some over-powered, over-noisy bike - but doesn't (or can't find the right sized) leathers, so instead goes out wearing bluejeans and a denim jacket. Just waiting for him to take a slip one of these days to see the folly.
Maybe he's actually wearing protective gear? Jeans with slide tolerant layers and padding are pretty common as warm weather gear and there are jeans style jackets as well. If you don't know what to look for it can be hard to tell the difference to regular clothing.
