Was it the person I met at an audax ride in Cheshire who had driven over from Bradford with his bike? He had remembered both of his wheels, but had forgotten to bring his cycling shoes ...
I have done
many daft things, so I'll just choose one at random! I rode over a broken bottle, and rather than stop to check my tyres for embedded glass I decided to carry on and hold my gloved hand against the front tyre to wipe off any nasties that might be there. Unfortunately, I chose to place my hand on the tyre behind the forks, rather then in front of the brake calliper ...