New to clipless pedals
I was visiting an ex-boyfriend who was a keen cyclist, and we decided to go out for a ride. We lived far apart and I didn't have a car, so I didn't have a bicycle with me (couldn't take them on the bus in them days). No matter, says ex Mr. Armadillo, you can borrow one. Fine, save for one little problem: the bike had clipless pedals. They're fine once you get used to them, but I wasn't, and I practiced for a bit. Once I felt comfortable, off we rode. Before we went anywhere, I decided that I needed some money, so we went through the drive-through ATM around the corner. So, pedal through waiting area, snap LEFT foot off pedal to stop at ATM...and instinctively try and put down my RIGHT foot, leaning to the right. It didn't snap out in time, naturally, despite my frantic ankle twisting. I hit my head quite hard on the cement surrounding the ATM. Luckily, I was wearing a helmet, or I probably would have ended up with a concussion.

Needless to say, I had the piss taken for the rest of the relationship on the strength of this incident.

Edited to add: For those not familiar with clipless pedals, you have to wear a special pair of cycling shoes to use them that have a cleat in the bottom. The cleat locks onto the pedal, and you have to twist your ankle to get it off.
(BlackArmadillo Avoided writing that article on, Thu 27 Dec 2007, 22:22, 3 replies)

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I've always wondered why 'serious' cyclists feel the need to be attach their feet to their pedals, especially considering how 'trick' cyclists jumping 20 feet in the air, hanging onto the handlebars with their teeth, facing backwards and whistling dixie seem to manage just fine when back on terra firma...
(misanthrope is so adjective he's verbing nouns!, Fri 28 Dec 2007, 10:34, closed)

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If you clip onto a pedal you can also pull the pedal up at the front as well as pushing it down at the back - it means you don't have to push so hard with your back foot and can hence exert less effort overall by using two different muscles instead of just one.
(hovishead, Fri 28 Dec 2007, 12:52, closed)

Clipless falls
Also means your foot won't slip off when accelerating hard. This happened to me once, foot hit tarmac, pedal hit me hard in the calf when it came back round, and I went straight over the bars. Wasn't my favourite thing.

Everyone who tries clipless has more or less the above incident - in my case, I rolled into a ditch full of nettles. And again. And again. After weeks of this, I gave up, and went back to clips and straps.
(Sammyhaswoefullyneglectedyou, Wed 2 Jan 2008, 19:00, closed)