If your partner gives birth to a stillborn baby or you suffer a heart attack on the day of your Jobcentre Plus appointment, you wouldn't expect to face benefits sanctions. But you'd be wrong.
In a different league entirely, I can personally sympathise with the man who found himself a job starting in three weeks but was sanctioned for failing to send out copies of his CV during that period, and the man who paid the price for going to a job interview (for a job he subsequently got) rather than attending his appointment. Back in 2006, had I been eligible for any benefits, they would have been docked when I missed an appointment due to a week of work experience I'd set up myself without any help whatsoever from the jobcentre...
On a lighter note, here are some of the most bizarre reasons given for visits to GPs - and some of the most absurd demands made of them by patients.
(Thanks to Abbie and Mhairi for the links.)