Mr Fry, sir, you are truly a national treasure, albeit rather young to be one. However, some of your advisors on QI are blackguards, scoundrels and, in all probability, footpads.
Twice (I think) on QI recently, you were advised to advise that slipping on a banana skin is a fallacy - a piece of folk mythology - and that banana skins are not slippery. Whoever fed you such information is a fool and a charlatan, as the large grazed area on my left knee-cap bears witness; indeed, had it not been for my determination to cling, limpet-like, to my shopping trolley in Canterbury's multi-storey carpark last week, I would most probably have suffered cranial injury.
It was one of those "slow-motion" events, where one knows what's happening but can't do a damned thing to stop it. My left leg slipped backwards at a rapid speed (my foot at the end of said leg having, as I soon discovered, encountered a discarded banana skin), causing me to kneel in a skidding motion, finishing the skid in a position where I appeared to be proposing marriage to the trolley.
The wonder of the whole event was that I managed to remove most of the skin from my knee while leaving the trouser leg that covered it completely undamaged. How can that have occurred? (Not that it matters: skin regrows, free of charge, whereas trousers are expensive.)