It can be dangerous if you're on a motorbike behind someone who flicks a smouldering cigerette end out of their window
I can see it now. Motorist casually flicks cigarette butt out of car window, it lodges in the leathers of passing biker, who starts smouldering, streaming black smoke and flames, ignites fuel tank, blazing fireball of death careens wildly down motorway embankment and explodes in children's playgrund.
How many needless deaths are caused in theis manner every day? Won't someone think of the children? 🙂
EDIT following mick's: if it's just about getting something in your eye when you're riding a bike at 100mph while not wearing the special thing that's designed to stop that happening then that's less exciting.